Abstract
According to consequent system of a SEI model, a model with vital dynamical and nonlinear incidence rate of saturated mass action is proposed. By making use of differential equation and characteristic of hepatitis C, we analyze the equilibria of the model with nonlinear incidence rate. When the basic reproduction number R0 < 1, the disease free equilibrium is stable and there are no endemic or two endemic . And we obtain the condition of a unique endemic equilibrium of the system.