Massive laser shot peening (LSP) is a promising surface modification technology to improve the properties of metallic materials. In this work, with the established FEM model, the dynamic propagation characteristics of stress waves by single round and square impact were investigated. The effect of three critical LSP parameters such as scanning patterns, overlapping rates and spot shape on the residual stress and the displacement deformation (U3) of 7075 aluminum alloy were further investigated under same spatial energy input. The simulation results were compared and validated with the reported research results. The spot shape has little effect on the residual stress field after a single impact while a better LSP treatment could be achieved by the massive square spot impact strategy. The snake scanning pattern was proved to be an optimized advancing pulse sequence compared with other two scanning patterns. The uniformity of compressive residual stress field and the displacement deformation (U3) curve were improved with the increase of overlapping rate.