To address the issues of high temperature rise and uneven temperature distribution in battery packs when using traditional channel cold plates, we propose a double-layer liquid cooling plate inspired by the structure of leaf veins. In this design, the upper flow channel of the cold plate comes into contact with the battery module for heat exchange, while the lower flow channel complements the areas not covered by the upper flow channel, ensuring more uniform heat dissipation throughout the module. Thermal simulation results for the double-layer leaf vein bionic channel liquid cooling plate indicate that it outperforms the traditional channel design. Moreover, it significantly improves the heat uniformity of the battery pack, effectively resolving the issue of a large temperature difference between the two traditional channel cooling systems. Furthermore, we optimized and analyzed the cooling plate's ability to remove heat under various structural parameters. The results reveal that the best cooling efficiency at low power consumption is achieved when the coolant outlet and inlet are positioned on opposite sides, the branch angle is set to 80 degrees, the branch channel width is 5 mm, the mainstream channel width is 7.5 mm, and the inlet fluid mass flow rate is 0.03 kg/s.