The main steam isolation valves in HPR1000 Nuclear Power Station play a vital role in ensuring safety. However, the unique structure of the valve room results in significant and uneven heat dissipation from the valves, necessitating a well-designed ventilation system to maintain an appropriate ambient temperature within the main steam isolation valve room. Drawing on previous power station design experiences, this study analyzes the heat dissipation capacity of the valves and the structural characteristics of the room. Based on this analysis, a ventilation system combining mechanical ventilation with localized cooling is designed. Additionally, the heat dissipation is verified using measured data, highlighting issues related to valve heat leakage. FLUENT numerical simulation software is employed to model the current scheme, analyze its temperature field, and validate the physical model. In response to the challenges encountered in practical measurements of the current scheme, four optimization proposals are put forward and validated through numerical simulations, providing valuable insights for the optimized design of ventilation systems in future nuclear power stations.