Abstract: Aiming at the relatively independent air conditioning system, battery thermal management system and motor thermal management system of a pure electric vehicle, this paper optimizes an integrated thermal management system for battery direct cooling in summer. Firstly, a battery heat generation model is built based on the experiment, and the battery cooling mode in the battery heat management system changes from liquid cooling to more efficient refrigerant direct cooling. Then, an optimization model of one-dimensional vehicle heat management system is built and simulated under the new European driving cycle. The simulation results show that, after battery direct cooling, the vehicle thermal management system has better temperature control effect on the passenger compartment, battery and its temperature difference. Compared with the liquid cooling system, its refrigeration energy efficiency ratio increases by 0.47 and the vehicle electric consumption reduces by 3.1%.