A new type of flow groove hydrodynamic mechanical seal used in nuclear main pump was taken as the research object.The pressure governing equation of the liquid film in the seal gap was established and solved by the finite difference method.The influence of the flow groove structure parameters on the sealing performance under specific working conditions was analyzed.The results show that the leakage rate and stiffness are the most sensitive to the change of the sealing gap.With the increase of gap,the leakage rate increases rapidly and the stiffness decreases sharply.With the increase of groove depth,groove length ratio,and weir width ratio,the stiffness first increases and then decreases and the peak value can be obtain in a certain area.When the number of streamline grooves is 12,the groove depth is 2 μm,the seal end gap is 1 μm,the groove length ratio is 0.6,and the weir width ratio is 0.6,the liquid film has better opening force,stiffness and stiffness-to-leak ratio,the fluid dynamic pressure effect produced by the sealing end face is significant,and the sealing performance reaches the better state.