BEIJING » At 30, Chen Kuo had what many Chinese dream of: her own apartment and a well-paying job at a multinational corporation. But in mid-October, Chen boarded a midnight flight for Australia to begin a new life with no sure prospects.

Like hundreds of thousands of Chinese who leave each year, she was driven by an overriding sense that she could do better outside China. Despite China’s tremendous economic successes in recent years, she was lured by Australia’s healthier environment, robust social services and the freedom to start a family in a country that guarantees religious freedoms.

"It’s very stressful in China — sometimes I was working 128 hours a week for my auditing company," Chen said in her Beijing apartment a few hours before leaving. "And it will be easier raising my children as Christians abroad. It is more free in Australia."

As China’s Communist Party prepares a momentous leadership change in early November, it is losing skilled professionals like Chen in record numbers. In 2010, the last year for which complete statistics are available, 508,000 Chinese left for the 34 developed countries that make up the Organization for Economic Cooperation and Development. That is a 45 percent increase over 2000.

Individual countries report that the trend continuing. In 2011, the U.S. received 87,000 permanent residents from China, up from 70,000 the year before. Chinese immigrants are driving real estate booms in places as varied as New York City, where some enterprising agents are learning Mandarin, to the Mediterranean island of Cyprus, which offers a route to a European Union passport.

Few emigrants from China cite politics, but it underlies many of their concerns. They talk about a development-at-all-costs strategy that has ruined the environment, as well as a deteriorating social and moral fabric that makes China feel like a chillier place than when they were growing up. Overall, there is a sense that despite all the gains in recent decades, China’s political and social trajectory is still highly uncertain.

"People who are middle class in China don’t feel secure for their future and especially for their children’s future," said Cao Cong, an associate professor at the University of Nottingham who has studied Chinese migration. "They don’t think the political situation is stable."

Most migrants seem to see a foreign passport as insurance against the worst-case scenario rather than as a complete abandonment of China.

A manager based in Shanghai at an engineering company, who asked not to be named, said he invested earlier this year in a New York City real estate project in hopes of eventually securing a green card. A sharp-tongued blogger on current events as well, he said he had been visited by local public security officials, hastening his desire for a U.S. passport.

"A green card is a feeling of safety," the manager said. "The system here isn’t stable and you don’t know what’s going to happen next. I want to see how things turn out here over the next few years."

Political turmoil has reinforced this feeling. Since early this year, the country has been shocked by revelations that Bo Xilai, one of the Communist Party’s most senior leaders, ran a fief that by official accounts engaged in murder, torture and corruption.

"There continues to be a lot of uncertainty and risk, even at the highest level — even at the Bo Xilai level," said Liang Zai, a migration expert at the University at Albany. "People wonder what’s going to happen two, three years down the road."

The sense of uncertainty affects poorer Chinese, too. According to the Chinese Ministry of Commerce, 800,000 Chinese were working abroad at the end of last year, versus 60,000 in 1990. Many are in small-scale businesses — taxi driving, fishing or farming — and worried that their class has missed out on China’s 30-year boom. Even though hundreds of millions of Chinese have been lifted from poverty during this period, the rich-poor gap in China is among the world’s widest, and the economy is increasingly dominated by large corporations, many of them state-run.

"It’s driven by a fear of losing out in China," said Biao Xiang, a demographer at Oxford University. "Going abroad has become a kind of gambling that may bring you some opportunities."

Zhang Ling, the owner of a restaurant in the coastal city of Wenzhou, is one such worrier. His extended family of farmers and tradesmen pooled its money to send his son to high school in Vancouver, British Columbia. The family hopes he will get into a Canadian university and one day gain permanent residency, perhaps allowing them all to move overseas.

"It’s like a chair with different legs," Zhang said. "We want one leg in Canada just in case a leg breaks here."

Emigration today is different from past decades. In the 1980s, students began going abroad, many of them staying when Western countries offered them residency after the 1989 Tiananmen Square uprising. In the 1990s, poor Chinese migrants captured international attention by paying "snakeheads" to take them to the West, sometimes on cargo ships like the Golden Venture that ran aground off New York City in 1993.

Now, years of prosperity mean that millions of people have the means to emigrate legally, either through investment programs or by sending an offspring abroad to study in hopes of securing a long-term foothold.

Wang Ruijin, a secretary at a Beijing media company, said she and her husband were pushing their 23-year-old daughter to apply for graduate school in New Zealand, hoping she can stay and open the door for the family. They do not think she will get a scholarship, Wang said, so the family is borrowing money as a kind of long-term investment.

"We don’t feel that China is suitable for people like us," Wang said. "To get ahead here you have to be corrupt or have connections; we prefer a stable life."

Perhaps signaling that the government is concerned, the topic has been extensively debated in the official media. Fang Zhulan, a professor at Renmin University in Beijing, wrote in the semiofficial magazine People’s Forum that many people were "voting with their feet," calling the exodus "a negative comment by entrepreneurs upon the protection and realization of their rights in the current system."

The movement is not all one way. With economies stagnant in the West and job opportunities limited, the number of students returning to China was up 40 percent in 2011 compared with the previous year. The government has also established high-profile programs to lure back Chinese scientists and academics by temporarily offering various perks and privileges. Cao from Nottingham, however, says these programs have achieved less than advertised.

"Returnees can see that they will become ordinary Chinese after five years and be in the same bad situation as their colleagues" already in China, he said. "That means that few are attracted to stay for the long run."

Many experts on migration say the numbers are in line with other countries’ experiences in the past. Taiwan and South Korea experienced huge outflows of people to the U.S. and other countries in the 1960s and ’70s, even as their economies were taking off. Wealth and better education created more opportunities to go abroad and many did — then, as now in China, in part because of concerns about political oppression.

While those countries eventually prospered and embraced open societies, the question for many Chinese is whether the faction-ridden incoming leadership team of Xi Jinping, chosen behind closed doors, can take China to the next stage of political and economic advancement.

"I’m excited to be here but I’m puzzled about the development path," said Bruce Peng, who earned a master’s degree last year at Harvard and now runs a consulting company, Ivy Magna, in Beijing.

Peng is staying in China for now, but he says many of his 100 clients have a foreign passport or would like one. Most own or manage small- and medium-size businesses, which have been squeezed by the policies favoring state enterprises.

"Sometimes your own property and company situation can be very complicated," Peng said. "Some people might want to live in a more transparent and democratic society."

© 2012 The New York Times Company