Abstract: The railway deck of Chao Ma Railway Bridge was made of stainless steel composite plates, which were Q420qE+316L and Q370qE+316L, with a thickness of 3mm for the clad layer and 16mm for the base layer.To improve welding quality, it was necessary to conduct welding process testing and evaluation tests for 2 kinds stainless steel composite steel plates. Based on the mechanical properties, chemical composition, and other factors of stainless steel composite steel plates, these were to clarify the welding materials for cladding, transition layer, and base layer. Based on the drawings and the Q/CR 9211—2015《Railway Steel Bridge Manufacturing Specification》,GMAW and FCAW were used to weld test plate. Typical plate thicknesses and grooves were selected for welding process tests, and the results showed that they matched the standard specifications, such as welding joint tension,side bending, low-temperature impact, intergranular corrosion, hardness, and other indicators. By conducting experiments, it could provide guidance for the planning and construction of welding processes for stainless steel composite steel plates.