For the current situation of low power density and limited space utilization of domestic new energy vehicle motor controller, a new energy vehicle controller with high power density is developed. The design theory of structureand hardware is combined with experimental verification to develop the controller. In the early stage, the controller is optimized by design analysis and finite element simulation. In the later stage, the performance of the controller is verified by experiments. The experimental results show that the motor controller has high efficiency and high power density, and has practical significance.