Abstract: Constant DC TIG welding, pulsed DC TIG welding and micro-plasma arc welding methods were used respectively to weld a type of aero-engine material of K4169 plate. The result demonstrated that the pulsed DC TIG welded joints have the optimal mechanical properties. The fatigue crack near the vent hole on the end of gearbox supporting plate were repaired by using the pulsed DC TIG welding, the radial distance and the distance from the base surface of internal and external hoops flange of the end of cracks located plate corresponded were measured and the effect of heat treatment on welding deformation was analyzed. The results illustrated that the repair of fatigue cracks near the vent hole of the end of gearbox supporting plate lead the radial expansion and circumferential distortion deformation occurred on the gearbox. Heat treatment will improve a significant function on the reduction of welding stress of repaired fatigue cracks of thin shell gearbox, which can reduce the welding deformation effectively and guarantee assemble dimension accurately.