Friction stir welding is a relatively new joining process, which involves the joining of metals without fusion or filler materials. In this study, the effect of tool pin profile on the mechanical properties of aluminum alloys AA2024-T351 joints produced by FSW was investigated. Four different tool pin profiles were developed, (straight cylindrical, taper cylindrical, triangular, and square) to weld the joints. All the welds were produced perpendicularly to the rolling direction for aluminum alloys. Tensile and bending tests were performed to evaluate the mechanical properties by using computerized universal testing machine. Among the four tools, square pin profile gives better tensile strength (265 MPa), elongation (4.9), maximum bending force (1450 N), and maximum welding efficiency (61%) in terms of tensile strength.