Abstract: The piezoelectric actuator was connected in series to the spot welding electrode. Based on the trigger control system,pulse vibration was applied to the welding spot at different stages during the spot welding process. Resistance spot welding test was conducted on the 6061 aluminum alloy through mechanical tensile and metallographic observation,by which the influence of time-selective piezoelectric vibration on mechanical properties and nugget size of spot welded joints was analyzed and researched. The results showed that in the full-stage pressure hybrid control and solidification-phase pressure hybrid control,the shear strength of the joint was reduced,and a large number of crack defects appeared in the joint. When applying pressure hybrid control in the current welding stage,shear strength of the joint increased,the size of the nugget increased significantly,and there were much fewer internal defects. During the 120 ms pressure hybrid control in the welding stage,shear resistance of the joint reached a maximum of 2. 11 kN. The pressure hybrid control at 60 ms after welding stage was compared with that at 60 ms before welding stage,nugget size increased and internal defects decreased.