This study tried to investigate the process parameters optimization of Friction Stir Welding on 5 mm similar double sided butt welded pure copper plate to improve tensile strength. To overcome the problem of fusion welding of copper in joint brittleness, oxidation, solidification and large distortion and to optimize the process parameters it needs adequate information of the tool dwell time, tool rotational speed, and traverse speed without this it was difficult to use the special features of copper such as high electrical and thermal conductivities, favorable combinations of strength and ductility, and excellent resistance to corrosion for many industrial applications. The study applied scientific methods, specifically statistical methods of both Taguchi and Gray relational coupled with Principal component analysis and selected universal milling machine as welding machine. Throughout the study, multiple quality characteristics like ultimate tensile strength and percentage of elongation are focused. The process parameters, namely Tool rotational speed, Traverse speed, and Dwell time are selected to optimized with respect to ultimate tensile strength and percentage elongation and the Taguchi quality design concept, an L9 Orthogonal Array table was chosen for the experiments. From the Gray relational analysis, a grey relational grade obtained and based on this value an optimum level of process parameters was identified. Furthermore, using analysis of variance method, significant contributions of process parameter have been determined. The confirmation tests are carried out to verify the results. The findings of the study confirmed that the selected process parameters were greatly influenced towards optimizing the quality characteristics of ultimate tensile strength & percentage elongation and the optimal process parameters was determined successfully so as to benefit quality weld through this approach and it showed that there exist a relationship between process parameters and responses besides all the considered factors are statistically significant to improve the tensile strength. And with the conclusions it was possible to get improved tensile strength of pure copper using friction stir welding, the process parameters optimized at tool rotational speed 400 rpm, traverse speed 30 mm/min and dwell time of 5 sec., and dwell time was much affecting the tensile strength. The implementation of friction stir welding process plays a vital role in successful quality improvement of pure copper and this method should further researched. Key words Tensile strength, Taguchi, Gray Relational: FSW, Copper, Analysis