A 12mm thickness 2A14M high-strengh aluminum alloy welding joint with improved mechanical performance was achieved by using the "friction stir welding + solidification + artificial aging heat treatment" procedure. The result show that tensile fracture occurs in the weld nugget zone of the welded joint without heat treatment.The average tensile strength is 192.3 MPa.The micro hardness distribution of the joint shows a π like shape with the peak area in the weld zone.The gap of hardness between different characteristic areas reach up to 60HRC.The presented post-weld heat treatment has refined the grains, improved the uniformity of the microstructure, optimized the distribution of the strengthening phase and weakened the tearing effects by the the sharp grain boundaries during tensile cracking process,thus significantly improved themechanical performances of the joint. As a result,the maximum hardness gap has been reduced to below 20HRC in the joint after the post-weld heat treatment.Moreover, tensile fracture may takes place in the base metal area or the weld seam with the tensile strength of up to 440 MPa which is 2.29 times of that of the joint without post-weld heat treatment. After post-welding heat treatment, probabilities of fracture appearance in base metal and weld nugget zone are same, both are 50%,and thus the goal of improving the performance of friction stir welded joints is achieved.