Abstract: This paper addresses the difficulty in heat dissipation of permanent magnet synchronous motors for flywheel energy storage.It takes a permanent magnet synchronous motor with a rated power of 300 kW and a speed of 10000 r／min as the research object.The loss and temperature field of the permanent magnet synchronous motor are simulated and tested by employing the magnetocaloric coupling method.The loss and heat distribution of the permanent magnet synchronous motor are studied.Meanwhile，the factors affecting the heat dissipation of key components of the motor are studied by the aforementioned thermal simulation model.Our results indicate the high temperatures are mainly concentrated in the permanent magnet and winding areas；reducing the width of the flow channel，increasing both water volume in the flow channel and radius of the flow channel effectively improve the stator heat dissipation performance；higher radiation rate leads to better heat dissipation performance of the permanent magnet.After improving the motor structure，the maximum temperature of the permanent magnet decreases compared with that before.Our research results may provide a theoretical basis for designing permanent magnet synchronous motors and optimizing their heat dissipation.