Abstract: In response to the problem of low pump volume efficiency in the actual operation of the dual internal meshing gear pump for a gearbox, the cause analysis is conducted on the pump structure. Based on this, the pump structure is optimized by adding rear end covers, fastening screws, and other measures; at the same time, comparative tests are conducted on the dual internal meshing gear pump before and after optimization. The test results show that the volumetric efficiency of the optimized dual internal meshing gear pump is significantly higher than that before optimization, indicating that the structural optimization design improvement can reduce pump leakage, thereby improving the volumetric efficiency of the pump and ensuring its good performance.