Through theoretical analysis, simulation and experiments, the fault characteristics of PV inverter generator are mainly researched. The PV inverter topologies and double-loop control principle are described, a simulation model of PV inverter generator is established, the output characteristics after the different short circuit fault are simulated, the main factors are analyzed, and the test data of a PV inverter is given. Compared with the traditional synchronous generator, short circuit current of distributed generator is quite different in basic composition, decay, amplitude characteristics, etc.