Abstract: The initiation and formation mechanism of cracking was analyzed during single-impulse resistance spot welding of 5052-O aluminum alloy(Al-Mg alloys). SORPAS software was used to simulate and compare cracking risk factor with multi impulses to that with single impulse. The effect of cracking initiation in HAZ of welded joint with multi impulses process was also discussed. According to the simulation results, analysis and verification were performed regarding the mechanism of suppressing cracking in specific area of HAZ with optimized electrodes and multiple impulses. The results show that cracking risk factor with multi impulses seemed lower than that with single impulse, and the influence of multiple-pulse technology on cracking was small. However, the annular grooves generated by the optimized electrode and combined with multiple-pulse process can completely inhibit the generation of cracking, and enhance the mechanical properties of the spot welded joint.