Abstract: The converter module of wind turbine works in high voltage,high current and high frequency switch state for a long time. If the heat generated cannot be dissipated in time,it will cause converter system failure and even lead to unit over temperature shutdown.This paper studies and analyzes the over temperature cause of SWITCH converter module in Jinfeng 1. 5 MW wind turbine Hedek water cooling system. It enumerates the relevant factors affecting heat exchange from the perspective of heat transfer. It puts forward the optimization scheme of improving three-way valve and disturbing wire,and points out the following optimization ideas. The results show that the temperature of converter module can be reduced by 5 ～ 10 ℃ by optimizing the three-way valve and replacing the spoiler wire of converter module,which ensures the healthy,safe and stable operation of the unit. The follow-up optimization control strategy improves the converter module over temperature. It has reference for improving the cooling cycle effect.