The permanent magnet direct drive system was studied from two aspects of direct drive structure and direct drive permanent magnet synchronous motor, and be applied on electric locomotive at the first time. The ground test and rolling test bench test of traction system were carried out, which showed that the system has the advantages of high efficiency, energy saving and so on.The implementation of this project provided a reference for the research and application of permanent magnet direct drive technology,and actively promoted the technical development of permanent magnet direct drive system in the field of rail transit in China.