A 3-D fluid numerical model of the mechanical seal with elliptical dimples was established based on multiphase flow cavitation model in Fluent to study the effect of suction on leakage rate.The influence parameters of the suction were analyzed theoretically.The results show that the leakage rate is reduced with the increase of suction,even to zero leakage rate.The influence parameters of the suction can be categorized into two types,the parameters which influence the hydrodynamic effect,such as velocity,differential pressure,cavitation pressure;the parameters which change the distance between the lowpressure zone and the outlet,such as orientation angle（the counterclockwise angle between the major axis of the ellipse and the horizontal axis),shape factor(length ratio of major to minor axis).The effect of these parameters on suction in mechanical seal with elliptical dimples was investigated.The results show that the suction is positively correlated with the velocity and shape factor,but negatively correlated with the differential pressure and cavitation pressure.The relationship between the suction and the orientation angle is similar to the sine function.