Aiming at the long‑term high temperature of mechanical seal water on the outlet side of one steam‑driven feed water pump in a thermal power plant， relevant troubleshooting was carried out. Comprehensive monitoring and horizontal comparison of operating parameters of the mechanical seal water system， an in-depth analysis of equipment structure and working principles， and a disassembly inspection of components related to the mechanical seal were conducted sequentially. The problems of insufficient cooling water flow and severely degraded hydrodynamic performance of the circulation device in the mechanical seal water system were resolved. The results show that the mechanical seal water temperature is reduced by 50.0 ℃ after maintenance， potential hazards in the feed water system are eliminated， and the safety and reliability of the unit are improved.