Abstract: In order to study the weld formation of GMAW surfacing, the welding experiment was carried out by using the unified adjustment mode of pulse GMAW process, and the theoretical analysis and experimental verification were carried out for the three different models including circle, ellipse and parabola weld models. The errors between the weld volume and total deposited metal volume were compared, and the optimal weld model was determined. The experimental results show that the error of the circle weld model is the smallest. When the welding parameters are voltage of 18.1V, current of 100 A and welding speed of 4 mm/s, the error of the weld volume is only 6.663 mm3. Based on the circular weld model and this group of welding parameters, the lap welding model was constructed and the lap amount was calculated, and the multiple pass lap welding tests were carried out. The experimental results show that when the lap amount is 6.928 mm, the weld is well formed and the surface flatness is high.