This work compared the parameters of friction stir welding (FSW) and under water friction welding (UWFSW) on the weld joint, such as tool rotation speed, transverse speed, and wall thickness, and compare the ultimate tensile strength (UTS) weld joint using the experimental work for FSW and UWFSW was performed using a new modified fixture to eliminate the post-process problems. Experiments were performed at three levels of three parameters: Wall thickness, tool rotational speed and travel speed using milling machine center by UWFSW and traditional FSW. The full factorial approach was introduced for statistical research. UTS i s measured as a reaction, meaning that the ultimate tensile strength achieved by welding the UWFS weld was greater than the conventional FSW weld. As a predictive research tool, regression analysis and variance analysis were used. From the study, it was observed that with minimal tool transverse speed, high tool rotation speed for UWFSW, maximum tensile strength is given, and that of traditional FSW.