This paper describes a new fault diagnosis method based on an equivalent-input-disturbance (EID) approach for distribution feeder with photovoltaics (PV) generation embedded. In this method, the faults are regarded as disturbances of system, which can be estimated by EID approach. Through analyzing the characteristics of the EID, the faults position can be located and the fault types can be identified. Firstly, a dynamic model of distribution feeder for fault diagnosis is built. Next, an EID estimator is designed. Finally, the simulation results demonstrate the effectiveness of the method.