Due to the feature of remote transmission by optical fiber, laser shocking peening with low pulse energy has a wide potential application in the field of on-site strengthening and life extension for large-sized mechanical components. In this work, finite element method was employed for the simulation of the laser shocking dynamic procedure and for the analysis of the static residual stress field in AISI 420 martensitic stainless steel, a typical material for the last-stage of steam turbine blades. Using Abaqus/Explicit dynamics, temporal distribution of the laser shock energy and von Mises stress were analyzed. Based on the Johnson-Cook plastic flow constitutive model, the residual stress and plastically-affected depth were comprehensively analyzed with parameters of pulse time, shot times, and peak pressure. The results indicated that laser shocking with low pulse energy has similar effect in terms of residual stress distribution with that obtained from high pulse energy. This trend also complied well with published experimental data.