In order to explore the influence of different flow channel designs on the heat dissipation performance, temperature uniformity and energy consumption of liquid-cooling plates, the Computational Fluid Dynamics(CFD) fluid-solid-heat coupled numerical simulation method is used for investigating the influences of their structural design parameters on the heat dissipation performance of a liquid cooling unit of electric vehicles. The results show that when the width of the central flow channel is increased from 6 mm to 31 mm, the maximum temperature difference on the surface of the thermal conductivty pad is reduced by 19.4%, and the flow resistance is increased by 14.6%，when the width of flow channels is reduced from the middle to both sides, the heat dissipation performance and temperature uniformity can be further improved, and the energy consumption can be controlled within an acceptable range. When the depth of flow channel is decreased from 5 mm to 2 mm, the maximum temperature difference is reduced by 36.7%, but the flow resistance is increased by 3.3 times, reducing the depth of the flow channel can significantly improve the heat dissipation performance and increase the energy consumption. Liquid-cooling plates with enhanced heat transfer structure channel or exchange of inlet and outlet in some cases can improve the heat dissipation and temperature uniformity, and also increase the flow resistance and energy consumption. It is concluded that the structure design of liquid-cooling plates can be supported by this research in order to improve the heat dissipation performance of battery module.