The emergency notice from the Ministry of Agriculture (search) said U.S. poultry products that have already arrived at Chinese ports would be returned or destroyed.
The notice, carried by the government's Xinhua News Agency, said China was suspending new import permits for U.S. poultry and canceling any permits already issued.
China's action follows similar bans on U.S. poultry by Japan, Malaysia, Singapore and South Korea, after officials in the U.S. state of Delaware reported avian flu in a flock there.
According to the Agriculture Ministry, in 2003 the country's total import of poultry meats and products was 709,000 tons -- 96 percent of which came from the United States.
That's a small fraction of China's poultry market; the country produced more than 9.9 million tons) of chicken meat alone last year -- 20 percent of total worldwide production.
China itself is a large chicken-farming country, and bird flu is confirmed or suspected in 14 of the nation's 31 regions.
China has slaughtered millions of fowl to try to contain the disease's spread and inoculated millions more.
The government has reported no human cases of bird flu.
In December, China banned beef products from the United States after a case of mad cow disease was reported there. That prohibition has not been rescinded.