Abstract: Welding deformation produced in welding process of SY35 platform will affect size of the platform and installation of cab and engine. Optimizing welding sequence and welding fixtures constraints is an important means to control welding deformation of SY35 platform. Research on MAG of SY35 platform was carried out in this paper, and a numerical analysis model of MAG welding deformation on SY35 platform was built to analyze influence of welding sequence and welding tool constraints on welding deformation of SY35 platform. Finally, welding sequence and welding fixtures that were conducive to controlling MAG welding deformation of SY35 platform constraint were proposed. The research results showed that the minimum deformation of SY35 platform bottom plate was 1.54 mm by the optimized welding sequence with targeted constraints. The research work of the paper will be helpful to guide welding deformation control of SY35 excavator platform, which has theoretical significance and engineering application value.