Friction stir welding (FSW) is a new and promising welding process that can produce low-cost and high-quality joints of heat-treatable aluminum alloys because it does not need consumable filler materials and can eliminate some welding defects such as crack and porosity. In order to demonstrate the friction stir weldability of the 2017-T351 aluminum alloy and determine optimum welding parameters, the relations between welding parameters and tensile properties of the joints have been studied in this paper. The experimental results showed that the tensile properties and fracture locations of the joints are significantly affected by the welding process parameters.