<p>The residual stress of S316L/Q345R stainless steel clad plate welded joints was investigated both before and after post-weld heat treatment (PWHT), employing simulations, X-ray diffraction and hole drilling strain-gauge method, the macroscopic and microscopic, along with stress corrosion resistance test. The findings reveal that residual stress is primarily concentrated near the fusion boundary and in the transition zone, with higher stress observed in the cladding layer compared to the base layer. During as-welded and PWHT, the X-ray diffraction and hole drilling strain-gauge method exhibited errors of 28.24% and 30.24%, respectively, in their residual stress measurements. A distinct boundary is evident at the fusion line of the transition layer and base layer accompanied by a visible layer of white decarburized; after PWHT, element diffusion occurs in the decarburized layer. The cladding layer exhibits relatively low stress corrosion sensitivity, and PWHT has a minimal effect on its stress corrosion resistance.</p>