The spiral shallow groove upstream pumping mechanical seal was taken as the research object,and the end face roughness was simulated approximately.The calculation model of clearance lubrication film flow involving surface roughness and liquid film cavitation was established,and the influence of surface roughness on the pressure distribution and cavitation of liquid film was analyzed.The studies show that the sealing end face roughness will increase the pressure of the liquid film high pressure area,the range is expanded and the larger the roughness is,the more obvious the effect is.The roughness of the non-groove area of the rotating ring has the largest effect,the roughness of the end face of the static ring has the second effect,and the roughness of the rotating ring groove area has the least effect.At low rotational speed (such as 1 000 r/min),no matter whether the end face is rough or not,the spiral grooves and rough elements do not cause the liquid film cavitation.At higher rotational speeds,the rough elements located in the low film pressure zone can lead to the micro cavitation of the liquid film.The roughness of the rotating ring groove zone has a certain inhibitory effect on the macro cavitation of the liquid film,and the larger the roughness is,the more obvious the inhibitory effect is.The roughness of the non-groove zone of the rotating ring causes the film pressure to rise and the cavitation zone to shrink,while the roughness of the end face of the static ring has relatively little effect on the film cavitation.The inhibition of the whole end face roughness on the cavitation is stronger than that of any local roughness,and the higher the rotational speeds is,the more obvious the inhibitory effect is.