Taking the spiral groove upstream pumping mechanical seal as the research object,the finite difference method was used to discretize the Reynolds equation,and based on the axial force balance condition as the iterative convergence criterion,the successive over relaxation (SOR) iteration method was used to solve the liquid film pressure distribution and related sealing characteristic parameters in the Mathematica software.The influence of different working condition parameters and structural parameters on sealing characteristics was analyzed.The results show that the pumping rate decreases nonlinearly with the increase of inlet pressure,and increases nonlinearly with the increase of speed,groove depth,and the ratio of groove length to dam length.The friction coefficient of the liquid film increases linearly with the increase of speed,and decreases nonlinearly with the increase of inlet pressure,groove depth,and the ratio of groove length to dam length.With the increase of helix angle,the pumping rate first increases and then decreases,while the friction coefficient of the liquid film shows an opposite trend to the pumping rate,indicating that there is an optimal helix angle which makes the sealing performance the best.Compared with the structural parameters,the working parameters have a greater influence on sealing performance.