They are also looking for better environments for their children—with better schools and cleaner air.
"Whether it is the perceived political instability or perhaps lack of educational opportunities, or pollution in the urban environments there, when you put those altogether ... and you mix that with the wealth that's present in China now, it really makes sense that there are folks there looking to explore these opportunities," said Peter Joseph of the Association to Invest in the USA, which represents investor-visa programs in the U.S.
(Read more: Countries woo rich Chinese with citizenship abroad)
Some say the capital flight and millionaire migration are normal consequences of rising wealth. Oliver Williams, of WealthInsight, said that the Chinese wealthy have about 13 percent of their wealth overseas—below the global average of 20 percent to 30 percent.
Still, much of China's offshore wealth is moved illegally or in the shadow economy. China maintains a closed capital account and Chinese citizens are generally not permitted to move more than $50,000 out of the country. So reliable data on exactly how much money is moving out remains unclear.
But the global buying spree by wealthy Chinese suggests the numbers may be far higher than reported. Wealthy Chinese buyers purchased more than $8 billion worth of residential real estate in the U.S. in the 12 months ended in March, according to the National Association of Realtors. China's share of foreign-purchased residential real estate has jumped 50 percent since 2011.
One of China's richest women, Zhang Xin of developer SOHO China, recently bought a townhouse in Manhattan for $26 million, according to reports.
(Read more: China has the youngest billionaires)
China's wealthy also are pouring money into collectibles and art. Billionaire Wang Jianlin and his company Dalian Wanda last month bought a Picasso at a Christie's auction for $28 million. Bidding from Chinese buyers was strong throughout the auctions, according to dealers and gallerists.
It's also going to wine and diamonds. Diamond dealers say more than half of today's collectible diamonds are going to Chinese buyers. And on Saturday, the world's most expensive case of wine—1978 Romanée-Conti—sold in Hong Kong for $476,000.
—By CNBC's Robert Frank. Follow him on Twitter: