Electrical pulse treatment was carried out on 2024–T4 aluminum alloy friction stir welding (FSW) samples. The results show that the strength of the sample decreases obviously and the elongation increases obviously after the treatment. When the effective current density is 135A/mm2

the tensile strength decreases by 25% and the elongation increases by 50%. The engineering stress-strain curve of the welding sample shows the zigzag fluctuation of PLC effect. After the aging treatment following by the electrical pulse treatment

the serrated fluctuation of tensile curve disappears. The elongation decreases slightly

while the strength increases. The material’s mechanical properties return to the FSW samples’ level. The tensile strength of the sample is 8% higher than that of the original joint after artificial reaging treatment

while the tensile strength is 4% higher than that of the original joint after natural reaging treatment. The microstructure shows that the grains are refined to different degrees in different areas of the joint after solution-treatment. The strengthening phase dissolves in the process of solution treatment

but re-precipitates in the process of reaging treatment. In addition

the volume and quantity of strengthening phase precipitated in nugget zone after artificial reaging treatment are larger in comparison to that after natural reaging treatment. The dissolution and precipitation of strengthening phase are the reasons for the change of mechanical properties and PLC effect of FSW samples after the reaging treatment following by solution treatment.