Abstract: Heat source parameters and cooling rate are the key factors affecting the repairing welding quality of titanium alloy blade. In the present work, the mathematical model of welding heat source is established based on the principle of pulse heat source superposition and Gaussian distribution. The finite element model of welding repair is established according to the solid structure of the fixture. The heat transfer process is modelled by COMSOL and the heat source model is verified by experiments.According to the heat transfer simulation results, the heat transfer characteristics, cooling structure and fluid parameters of the fixture are analysed. The maximum temperature variation after adopting the cooling method is analysed and the welding experiment is carried out by establishing the parameterized surface of typical positions. The results show that the heat source model is in good agreement with experimental measurements. The heat exchange method can effectively improve the repairing welding quality.