The work aims to solve the problems of high temperature and large temperature difference of lithium-ion battery pack in the traditional thermal management system during the charging and discharging process. The liquid cooling method was taken as the main means to design a single-inflow and single-outflow microchannel structure and two double-inflow and single-outflow microchannel structures on the basis of the traditional serpentine cooling channel, and a new type of high-thermal-conducting material, graphene film, was adopted as the auxiliary heat dissipation material. Based on the finite element simulation software, a comparative analysis was carried out from four perspectives:maximum temperature, temperature difference, temperature rise and fluid pressure of the battery pack. The maximum temperature of the optimized battery pack was reduced from 36.4 ℃ to 36 ℃, and the temperature difference was reduced from 8.7 ℃ to 3.9 ℃, which improved the heat dissipation capability and temperature consistency of the battery pack. The double-inflow and single-outflow structure is better than the single inflow-single outflow structure, in which the double corrugated serpentine is the optimal liquid-cooling microchannel structure, and the adoption of graphene film can further improve the temperature consistency of the battery pack.