Abstract: Objective The aim was to conduct application experimental research on the newly developed S31603 austenitic stainless steel and Q420qENH weathering steel clad steel plate. Methods Welding performance of steel plates was evaluated through the highest hardness test of welding heat affected zone and oblique Y-groove welding crack test. Welding procedure qualification test were conducted for different application scenarios of clad steel plates. Mechanical performance testing, metallographic analysis and other methods were used to study welded joints. Results The results showed that the highest hardness of welding heat affected zone on the base side of S31603+Q420qENH clad steel plate with a thickness of 3 mm+16 mm was 287 HV10, which was lower than 350 HV10. Under the condition of no preheating, no cracks were found in the weld surface and section of the inclined Y-groove welding crack specimen. Welding procedure qualification test was qualified, and no adverse microstructure was found in the weld. The intergranular corrosion test of the cladding was qualified. Conclusion S31603+Q420qENH clad steel plate had no tendency for welding hardening, did not require preheating before welding, had good weldability, and welding procedure qualification test results met the requirements of “Code for fabrication of railway steel bridge”. The test results could be used as a basis for preparing welding processes for actual bridge applications.