The development of power electronics technology has made it possible for all-electric combat vehicle (AECV). The high-voltage power supply system, high-temperature working environment and high power density requirements of AECV bring new challenges to the design of the permanent magnet synchronous motor (PMSM). In this paper, the electromagnetic design and thermal design of PMSM for AECV are taken as the research object. A high-speed PMSM with rated power of 1.5kW and rated speed of 18000r/min is designed. In order to accurately calculate the losses in the PMSM under the space vector pulse width modulation (SVPWM) voltage, this paper uses a multi-physics simulation method. Finally, electromagnetic simulation and thermal simulation of the motor are carried out. The results show that the motor meets the design requirements.