Abstract: Weldability test on 2 mm thick ABS plastic and 6082-T6 aluminum alloy sheets were conducted by friction stir spot welding. The cross-section of resultant specimen was observed and analyzed, and the mechanical properties of the joint were measured. It is found that good connection could be obtained with aluminum alloy on the top and plastic at the bottom. The optimal welding parameters were rotation speed of 400 r/min and welding time of 30 s. The maximum tensile shear load of the welded joints reached 3.31 kN. The spot joints failed with two fracture modes.