A partial lubrication model was established by using MatLab software to investigate the sealing performance of reciprocating seals,which consists of the analysis of elastic mechanics,fluid mechanics and contact mechanics.The effects of surface roughness and reciprocating velocity on the dynamic sealing performance,including friction,leakage as well as film thickness,were studied based on the partial lubrication model.The sealing mechanism of reciprocating seals was discussed.The results show that the reciprocating seals experience partial lubrication conditions,which consists of fluid pressure and asperity contact pressure.The critical roughness and σ≥σc and critical velocity uc are observed.When the surface roughness is less than σ≥σc,the internal leakage is decreased with the increase of surface roughness during the instroke.Otherwise,the external leakage is increased with increase of surface roughness during the instroke.Increasing of reciprocating velocity will result in a decrease of the external net leakage when the reciprocating velocity is less than the critical velocity uc.On the contrary,an increase of reciprocating velocity causes an increase of the internal net leakage under the conditions that the velocity is larger than the critical velocity uc.With the increase of surface roughness,the film thickness and instroke friction are increased,while the outstroke friction is independent of the surface roughness.The increasing of reciprocating velocity leads to a significant increase of film thickness and decrease of instroke friction,while the reciprocating velocity has little effect on the outstroke friction.