Dissimilar welding or joining dissimilar metals using welding process, Micro welding or welding process for joining metals less than 1 mm, have unique problem difference of thermal properties from metals lead to melting processes and thin of metal affected easy to filed (hole). Welding parameters affected to weld join performance, this study discussed effect of Micro Friction Stir Spot Welding (Micro-FSSW) parameters to performance of both thin plate of 0.5mm of Copper with 0.5 of aluminium which were joined by welding process. Tensile test was used as the mechanical performance analysis. Micro-FSSW succeeds to joint thin Cu and Al plate. Weld joint welded by shoulder diameters 6 mm, welding force 50 kgf, and 3000 rpm of rotation speed (constant), and welding time 60 sec could be achieved 401.7 N of maximum load.