Abstract: To study the pressure loss in the runner during the rotating transmission of fluid slip ring，the local pressure loss of the fluid slip ring is simplified and the theoretical estimation method of the pressure loss of the fluid slip ring is proposed.Based on the finite element software Comsol，the numerical analysis of the fluid slip ring is made to study the effect regularity of different fluid inlet and outlet angles and the width of the annular runner on the pressure loss of the runner.Our results show the relative numerical simulation result error of theoretical calculation and experimental test of fluid pressure loss is within 20%.The theoretical calculation method proposed in this paper can guide the rapid evaluation of fluid slip ring pressure loss.The pressure loss of fluid slip ring increases at first and then decreases gradually with the increase of the angle of fluid inlet and outlet.When the angle of fluid inlet and outlet is 30，the pressure loss of fluid slip ring is the highest.The pressure loss of the fluid slip ring gradually decreases with the increase of the width coefficient of the runner.When the width coefficient increases to a certain value，the pressure loss reduction effect of the runner is weakened，and the optimal runner width is 0.8-1.2 times of the design width of the equal section.