Lip seals are widely used in industry.Reverse pumping rate and friction torque are two critical parameters for evaluating their performance.An analytical model of lip seals based on the reverse pumping mechanism of lip seals was presented.Numerical analysis of micro unit containing a single asperity and mixed lubrication model were involved in the development of the analytical model.The static pressure distribution was obtained using FEM,general equations of the reverse pumping rate and the friction torque were derived based on the numerical analysis,and the undetermined factors were calibrated through experimental results.The model was proved to be useful by successfully predicting numerical and experimental results from public literatures,where a lip seal with different design parameters was adopted.Compared with numerical process,the analytical equations provide a more direct and efficient way to predict the working behaviors of lip seals,therefore is more practical in lip seal design.