Combined with electric vehicle (EV) applications, the structural characteristic for flux weakening (FW) operation of permanent magnet synchronous motor (PMSM) was analyzed in this paper and based on the mathematical model of PMSM, this paper describes the different methods of flux weakening control applied in vector control. Limited by power supply voltage of vehicle, the increase of higher speed must rely on flux weakening control. In order to achieve optimal use of PMSM, scholars at home and abroad have proposed a variety of methods based on the model parameters or robust control, with the flux weakening region subdivided into FW region I and FW region II. The paper summarizes the research results in recent years, and sorts various control methods in FW region I and FW region II with advantages and disadvantages stated. Finally, the development trend of electric vehicle control system optimal design in the future was briefly discussed.