Abstract: When the viscoelastic artificial boundary is applied to explicit dynamic calculation, the stability conditions of the boundary area are more stringent than that of internal domain due to the stiffness and damping of artificial boundary, which limits the application of viscoelastic artificial boundary in large-scale explicit dynamic analysis. Based on the analysis of stability conditions and influencing factors of the viscoelastic artificial boundary in explicit time-domain stepwise integration algorithm, this study proposes a method to improve the numerical integration stability by introducing the lumped mass to the artificial boundary and thus develops an improved viscoelastic artificial boundary. In order to obtain the reasonable mass value of artificial boundary, the stability analysis method based on local boundary subsystem is used to derive the stability conditions of the improved viscoelastic artificial boundary, and then the recommended value of the lumped mass is obtained through comparative analysis. After adopting this recommended value, the stability condition of the artificial boundary area is looser than that of the internal calculation domain. Thus the overall numerical model is controlled by the internal domain. Then the conventional stability discrimination method can be used to estimate the critical integration time step that satisfies the stability condition. Numerical examples show that the method for improving the stability of viscoelastic artificial boundary proposed in this study can increase the calculation efficiency without losing the calculation accuracy. Therefore, it has strong practicability.