Firstly, through the reading and summarization of domestic and foreign literatures, this paper studies and analyzes the cooling methods of battery packs and motors, and finds the solutions for the cooperative thermal management of electric vehicle power systems and their existing problems. Secondly, the structure of the electric vehicle parallel cooling system was studied and analyzed, and the parallel liquid cooling scheme was confirmed. The model of the parallel cooling system was established by using GT-SUITE simulation software. The parallel cooling system model motor is located on the main branch road. When the system starts running, the coolant will flow through the motor to cool it, and the battery is located in the secondary branch. On the road, an event controller controls the battery temperature to be in the range of 25 ° C to 30 ° C. When the battery temperature is not within this range, the event controller will cause the coolant to flow through the battery, so that the battery temperature returns to 25-30 ° C.