The power circuits of several urban rail transit vehicle traction systems were analyzed, and the simplification design ideas were developed. Then, a whole design method for urban rail transit vehicle traction inverter from the power circuit, electrical parameters and cooling system was provided. The simplified traction inverter could satisfy the different demands of vehicle control, bogie control, axle control. The simplification design methods for traction inverter were proved reasonable and feasible by the experimental results of the existing project, which could satisfy the urban rail transit vehicle requirement.