Frictional heating system and permanent distortion under melting heat are mechanisms behind Friction stir welding (FSW) of materials. The main aim of this investigation was to examine the influences of mechanical characteristics of friction stir welded dissimilar aluminium alloys (AA3103 & AA6063) on various joining parameters and to perform ANSYS analysis to assess the temperature distribution in the welded area. Properties like hardness and tensile strength were investigated to assess the mechanical performance of the welded alloys by considering parameters like welding speed, tool rotation speed, and the applied axial load. It could be seen from the results that a rotational speed of 1300 rpm, welding speed of 30 mm/min and an axial load of 9 kN provided maximum tensile strength and hardness to the FSW specimen. Temperature distribution during the welding was visualized using ANSYS.