The article examines the effect of welding tool displacement on copper and aluminum during friction stir welding on the formation of microstructure and mechanical properties of a dissimilar weld. The corresponding welding modes were considered in the work: welding tool rotation speed 900 rpm, welding speed 25 mm/min, mixing varied from 0 to 3 mm for copper or aluminum. The most optimal displacement during friction stir welding was the location of the pin of 0.5 and 1 mm on copper, which allows the formation of a composite structure of the core and the thermal deformation zone. At these positions of the tool pin relative to the line of contact of the metals, the mechanical properties of the weld are closer to those of the most ductile material (aluminum). The welding mode parameter (displacement) affects the formation and volumetric content of intermetallic layers. If the thickness of the intermetallic layers does not exceed 4-5 µm, then increased values of the mechanical strength of the welded dissimilar joint are observed.