Abstract: Aiming at the fillet welding of a 5 mm thick S32168 stainless steel frame structure, CMT and CMT+P welding experiments of T type joint of 5 mm thick plate were carried out, the influences of CMT, CMT+P modes, arc length correction and pulse correction parameters on the weld appearance were compared. Optimal welding parameters were obtained and the welding procedure qualification was performed according to NB/T47014-2011 standard. The results show that welded joints with complete root fusion could be obtained using CMT mode but pore exists in the root zone, and the weld appearance is convex and not beautiful. Plat or slightly concave fillet weld with complete root fusion and no pore could be obtained by using CMT+P mode matching with proper arc length correction and pulse correction parameters, and the weld appearance is beautiful and the weld procedure is qualified. The weld appearance, inner quality and post weld deformation of the frame structure can meet the drawing and manufacture requirements by using designed fixture, proper welding sequence and optimized welding parameters.