Abstract: The twin gear pump is an auxiliary device integrated with the turbine-driven feedwater pump, which is one of the key components of the secondary circuit of a nuclear reactor. Stable operation of the turbine feedwater pump ensures a reliable water supply to the steam generator. This paper provides a brief introduction to the twin gear pump and addresses the problem that the safety oil pressure of a specific twin gear pump could not be stably maintained within the normal range during operation and commissioning. The pump was disassembled and analyzed to identify the root cause of the failure. On this basis, the structure of the twin gear pump was optimized, and the effectiveness of the improvements was verified through performance tests. The experimental results show that the optimized twin gear pump successfully eliminates the original problem and ensures the normal and stable operation of the turbine feedwater pump.