Cells are the basic component units of organisms, and reflect the physiological state of creatures. The mechanical properties of a cell reflect the cytoskeletal structure and composition and are closely related to the cellular biological functions and physiological activities. Therefore, modeling the mechanical properties of single cells provides the basis for analyzing and controlling the cellular state. Previously, we developed a dynamical model with cellular viscoelasticity properties as the system parameters to describe the stress-relaxation phenomenon of a single cell indented by an atomic force microscope (AFM). However, in this model, the effect of the AFM cantilever was neglected and the viscoelastic properties of both the cell and the AFM cantilever are considered as a whole in the model. In this study, we modified the model by considering the AFM cantilever as an independent factor and the elasticity of AFM cantilever and the viscoelasticity of cells are decoupled. The modified model can characterize the mechanical properties of single cells without the influence of AFM cantilever.