The purpose of this study was to discuss the microstructure, recrystallization, and mechanical property evolutions in the heat-affected zones and fusion zones during dissimilar stainless steels welding. The morphology, quantity and chemical composition of the δ-ferrite were analyzed by using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and electron probe micro-analyzer (EPMA), respectively. The recrystallization phenomenon was evident with the second pass heat-affected zone (HAZ-2) and indicated equiaxed grains after second pass welding. The contents of δ-ferrite exhibited the highest value of all situations in the first pass fusion zone (FZ-1) during the first pass welding. Furthermore, the solidification mode of fusion zones transformed from massive as well as acicular δ-ferrite into lathy and skeletal structures as increased the welding pass number from 1 to 3.