A numerical method that predicts the paper velocity at the roller transfer unit in an electrophotographic system is presented including the roller slip characteristics and the tension in the paper. The roller slip characteristics are derived from the measurement of the relative velocity between the roller and a paper under an external force. The paper feeding simulation is used to calculate the tension in the paper among the registration rollers, the roller transfer unit and the fuser rollers. The paper velocity at the roller transfer unit is predicted solving the equilibrium equation between the tractions given by the transfer roller and the photoreceptor drum and the tensions in the paper. The predicted velocities agree well with those from experiments, which is based on the time interval sensing of the pattern of lines printed on papers.