Abstract: Since the Jinglong No.2 power generation unit was put into operation, there has been a large vibration on the left side of the boiler wall, and the flow field in the furnace was analyzed by using the full-size 1:1 modeling of the boiler internal structure. Through the hot state test, cold state check, CFD（computational fluid dynamics） flow field analysis, modal analysis and other methods, the main reason for the vibration of the furnace wall was the existence of unstable smoke airflow in the boiler. According to the causes of vibration, the internal and external structure of the boiler is optimized, and the vibration intensity of the furnace wall is reduced by 77% ～ 88%, which further improves the safety of the boiler operation.