In Shanghai, a 2015 rule relaxed the criteria for green card eligibility for local foreign residents, said Becky Xia, a Shanghai-based partner at Fragomen, an international immigration law firm. Although applicants must still show four years of residency and a yearly salary of at least 600,000 renminbi, or about $87,000, she said, the new rule no longer requires them to be top executives.

Ms. Xia said that Fragomen had seen a 50 percent increase in the past year in clients seeking help with green card applications. Most, she said, were Europeans in the information technology sector who oversee manufacturing in China. She expected the number of green cards issued in China to rise, she added, partly because foreigners in business who have passed China’s retirement age — 60 for men and 55 for white-collar women — are not eligible for work visas and could apply for green cards instead.

From an employer’s perspective, “I would think there are more options for getting the talent you want,” she said of Shanghai’s new rules. She added that green cards, unlike work permits, were not tied to job contracts and were valid for renewable 10-year terms.

But Chinese immigration and residency policies that have been enacted since 2013 have also become more restrictive toward less valued workers, especially the African traders and entrepreneurs who have settled in the southern city of Guangzhou since the early 2000s, often by overstaying their visas, experts said.

Gordon Mathews, an anthropologist at the Chinese University of Hong Kong who has studied communities of Nigerian traders in Guangzhou, said that the police there had cracked down on people who had overstayed their visas after dozens of Africans, mostly from Nigeria and Mali, were arrested in an August 2013 drug raid.

Mr. Mathews said that many African and Arab traders in Guangzhou overstayed their visas because the official limit on their stays — typically two weeks or a month — often did not provide enough time to commission a factory order and see it through to completion. But the government appears unwilling to loosen that rule, he added, and foreign traders who obtain legal residence permits are generally limited to one-year stays with no guarantee of renewal, even if they have Chinese spouses or children.

“The whole issue is: Can foreigners become Chinese?” he said. “Yes, I know there’s a green card system and so on. But on the ground, it appears doubtful.”