In this paper viscoelastic analysis based on MSC.Marc is discussed. Based on MSC.Marcs opening program interface, the generalized Kelvin model comprised by arbitrary(n≥2) kelvin models in series is developed. The developed subroutine is proved to be reasonable and feasible though an example. The viscoelastic deformation law caused by deviation stress is the same as the bulk stresss viscoelastic deformation law when the viscoelastic deformation FEM formula is expressed by stress tensor in existing documents. This is not always right to the complicated engineering material. So, attention must be paid to analyzing viscoelastic problems.