China's Agriculture Ministry says the outbreak of the deadly H5N1 virus was found in Zhongwei city. Details on how many birds were affected or whether it was among farm-raised poultry were not immediately available.
China has reported nearly 40 outbreaks of bird flu in birds and poultry across China over the past year. The country's human bird flu infections stands at 19, 12 of whom have died.
The World Health Organization says the H5N1 strain of the virus has killed at least 130 people since reappearing in Asia in 2003.
Most of the victims have gotten the disease from animals, but health experts fear the virus may change into a form easily passed between humans.
Some information for this report was provided by AFP and Reuters