Multi-pass welding process is one of the most applicative methods of welding in various industries. In this paper, temperature and residual stress distribution due to three pass welding of two plates made of AISI 321 stainless steel having different thicknesses is studied. Welding process consists of three welding passes of two Shielded Metal Arc Welding (SMAW) process and one Gas Tungsten Arc Welding (GTAW) process. First, the benchmark plates are manufactured and welding process is performed. The transient temperature distribution during the welding process is recorded using thermocouples attached to the welding plates. First this process simulated experimentally and temperature distribution during to welding process was measured using thermocouples. Furthermore, the final residual stress distribution after welding process is measured using incremental center hole drilling technique (ICHD). The three pass welding process was then simulated using ABAQUS finite element (FE) code. The finite element model consists of temperature-dependent properties of base metal and weld metal. Furthermore, moving heat source and the element-birth technique is implemented in FE model. Experimentally measured temperature and residual stresses provide an in-depth knowledge insight the complicated welding process. . Comparing between the results shows that the numerical predictions and experimental measurements have good agreement and therefore the FE developed model can be employed in designing and evaluating of welded structures.