Effective thermal management is essential for ensuring the safety and high performance of electric vehicle battery packs. This paper investigates the optimization of a fishbone flow channel structure through three strategies: a tapered main channel, reduced rear branch width, and the addition of branch flow channels. Numerical results from ANSYS Fluent indicate that compared to the baseline fishbone channel, a tapered design with a 2 mm outlet width reduces the maximum temperature to 37.21°C, a 0.12°C decrease, and lowers the temperature standard deviation by 0.04°C to 0.51°C. However, a 12% pressure drop increase offsets the 7% gain in the heat taken away by the coolant, limiting the improvement in the comprehensive performance evaluation factor to only 0.7%.Reducing the rear branch width to 2 mm constrains the temperature standard deviation to 0.50°C, which is 0.05°C lower than the original channel, with minimal impact on other metrics. Expanding branch channels is the most effective strategy for heat transfer enhancement. Specifically, a structure with a 6 mm branch length reduces the maximum temperature by 0.54°C to 36.79°C and decreases the temperature standard deviation to 0.52°C. Furthermore, this configuration achieves an 18% reduction in pressure drop, while the heat taken away by the coolant and the comprehensive performance evaluation factor increase by 3% and 15%, respectively. These findings provide a quantitative basis for designing high-efficiency liquid cooling plates.