To analyze the feature of three Avian - human Influenza cases in Sichuan province, and to provide scientific reference for the prevention and cont rol. Methods According to the epidemiological investigation plan of Avian - human Influenza , case investigation were made for all these cases , which including the process of falling ill , treatment , laboratory detection , possible infection source , transmission route , risk factors , ect.,al . Results One of these cases was not exposed to the dead or illed fowl , but the others were exposed to. There was no evidence to manifest that the dead or ill fowl were infected with Avian Influenza ; symptom of the cases looked like flu in incipience ; the Avian Influenza virus H5N1 was detected from the samples of t rachea excrete of two cases , RNA testing of the t rachea excrete sample of the other case was positive. RNA testing of the pharynx sample of three cases were negative. Conclusions Three cases are pathogen confirmed patients. It is necessary to try the best to collect sample of t rachea excrete of the case. The diagnosis of Avian - human Influenza is not depend on whether Avian Influenza in fowl or not. Infection source , transmission route , and the influential factor of Avian - human Influenza would be assured in further study.