Objective To understand the source of infection and dissemination of the way through the field investigation and analysis on the first family clustering avian influenza A(H7N9), in order to provide reference for avian influenza A(H7N9) prevention and control in the future. Methods Field epidemiology was conducted to investigatethe process of incidence and treatment, the history of suspected exposure, and epidemiological associationand close contact persons of 2 patients. Specimens from patients and live poultry markets were collected to carry out the nucleic acid detection of influenza virus. Results This family clustering avian influenza A(H7N9) included 2 patients as mother child relationship. First case was onset on February 4, and she had a clear live poultry market exposure history before onset. Secondary case was onset on February 15, and he had both the history of live bird markets exposure, and the close contact history with first case before onset. A total of 38 specimens were collected and tested, 13 of them were detected H7N9 positive, which all came from the live poultry markets. Conclusion Live poultry markets exposure may be the source of infection of the first case. The infection sources of the secondary case both may be exposed to the live poultry markets and a human to human transmission from the first case. In H7N9 epidemic investigation and disposal, the management of close contact persons and personal protection work should be well done.