Soft tissue deformation is an important part of virtual surgery simulation systems.Real-time and realistic simulation of soft tissue deformation in humans is crucial for virtual surgery simulation systems.Soft tissue deformation simulation mainly applies a linear and viscoelastic biomechanical model;however, this model loses numerous properties of soft tissue.As a consequence, a realistic representation of soft tissue deformation is difficult to achieve.This paper proposes a nonlinear viscoelastic element-free Galerkin model to solve current problems related to soft tissue deformation.The proposed model increases adjustment function compared with a linear viscoelastic model.Therefore, the proposed nonlinear viscoelastic model can efficiently simulate real properties of soft tissue.Experimental deformation simulation results of the human liver show that the proposed method is valid.