Due to the strict requirement of small size and light weight, the motors used in new energy vehicle had the characteristics of high power density, light weight, small volume and compact structure, which inevitably had a significant influence on the heat dissipation of motors. Thus, the motors cooled by water jacket had emerged as a mainstream, but how to set up the efficient heat conduction passage from the internal motor to the shell was still one of the important problems restricting the motor performance. In order to improve the thermal conduction efficiency of windings, the potting gum with relatively higher thermal conductivity was filled into the stator slot winding and the end winding. The fluid field and temperature field of the potting motor and the unpotted motor were studied using the method of fluid simulation. The simulation results were verified by experiment using the existing experimental platform. The results showed that the heat dissipation condition of the end winding and the winding in the slot is improved effectively after the motor was potted, the temperature gradient between the end winding and the slot winding was reduced, and the maximum temperature of the motor winding was reduced by 22 ℃.