In the clearance seal at the micro/nano scale,the liquid flowing through the interface with different wettability will produce different degree of boundary slip at the solid-liquid interface,which will affect the flow state and leakage.In order to deeply study the relationship between the wetting characteristics of sealing pair and the leakage,based on the principle of molecular dynamics,a clearance seal model was established to simulate the boundary slip and leakage of surface water molecules at different wall velocities with different wettability.The results show that the maximum shear stress on the wall increases linearly with the increase of the wall velocity,and a slight boundary slip still occurs on the hydrophilic wall under the high shear speed.With the increase of the shear rate,the slip length and leakage tend to be stable.In the actual production,the shear rate is small,the shear stress is not enough to produce boundary slip,and the water molecules are easy to adsorb on the wall,resulting in larger leakage.Therefore,at low shear rate,the wall wettability has little influence on the leakage.However,when the shear rate is high,the shear leakage of the wall with poor wettability is smaller,so the better sealing effect can be achieved by using hydrophobic coating on the sealing surface.