Friction stir welding (FSW) is a solid-state joining process that uses a non-consumable tool to join two facing workpieces without melting the workpiece material. This is performed by using a milling machine. Heat is generated by friction between the rotating tool and the workpiece material, which leads to a softened region near the FSW tool. Magnesium alloy is the most widely used due to its excellent corrosion resistance, high ductility and reflective finish, lightweight material used in industries and aerospace, the selected material was welded with Friction Stir Welding (FSW) process, by using a combination of different tool rotation speed (1500 rpm, 2500 rpm, 3500 rpm) and welding speed (10 mm/min, 30 mm/min, 50 mm/min) as welding parameters. The weldments are welded by changing the tool length, the material of tool, depth of indentation, by changing tilt angle and the welded joints were tested using the universal testing machine, Ultimate Tensile Strength and hardness test. By using the above testing methods various parameters and grain structure of welded joints are studied.