Abstract: In order to study the quality of resistance spot welding joint, three groups of dynamic data were analyzed and drew to curve during the resistance spot welding of aluminum alloy 2A12, namely, the electrode force, the electrode displacement and welding current. The results show that the change tendency of the electrode force was depressing slightly at the beginning of the welding, then a small increase with slight fluctuations, and finally a downward-sloping trend. Unqualified weld was formed when the force is under or over the normal stress at each stage. The rising rate of the displacement curve is related to the welding current and the energy efficiency. The shape of the displacement curve between the maximum displacement and the loading forging force is related to the amount of melting metal and the size of the softening zone.