Solidification crack was a common welding defect in welding of aluminum alloy.Whensolidification shrinkage and heat shrinkage of thevulnerable zoneand its surrounding solids were hindered, it willcause grain boundary cracking owing to insufficient supply of liquid metal.Therefore, cracks generally appear in the middle part of aluminum alloy welding spot at the late stage of solidification. Compared with continuous laser, pulsed laser could meet more precise heat input control and was widely used in aluminum alloy sheet welding.In this research, by designing different pulse shaping to improvethe solidification condition of the5083aluminum alloy pulsed laser welding spot, the numerical simulation was used for analyzing the solidification rate and temperature gradient of molten pool.Application of ramp-down pulse decreased crack cross-sectional area from 420475 µm2 to 0, and step-down pulse could also effectively control the crack radius. The results showed that effect of suppressing solidification crack on the horizontal direction of the welding spot was obvious to the vertical direction. Using ramp-down or step-down pulse shaping also reduced the volume of the liquid molten pool at the end of the laser process, which decreased the shrinkage stress at the late stage of solidification.