Abstract: The influence of secondary welding on the microstructure and mechanical properties of Q＆P980 steel spot welding joints was investigated. It is found that the 6 kA secondary current welding after primary spot welding remelts the primary welding microstructure of Q＆P980 steel, restructures the secondary welding core, refines the martensite structure and decreases the shrinkage cavities in the secondary weld core. Hence, the hardness of secondary welding core, shear load, peel load and energy absorption performance of spot welding joints are obviously improved compared with those of primary spot welding joint. However, 5 kA secondary current welding only tempers the martensite structure of primary welding core, so that the hardness, strength and energy absorption performance of the welding joints are lower than those of primary spot welding joint. Meanwhile, the 7 kA secondary current welding is easy to produce overheating, which causes the shrinkage hole reappeared in the secondary welding microstructure. Although its hardness, strength and energy absorption performance are higher than those of the primary welding joint, it is lower than that of the 6 kA secondary welding joint. Therefore, in order to improve the mechanical properties of Q＆P980 steel spot welding joints, the key is to adopt proper secondary welding current.