To investigate the influence of surface roughness on the elastohydrodynamic lubrication characteristic between the slider and the slideway of tripod slider universal coupling of tripod sliding ball universal coupling.Based on the linear contact isothermal elastohydrodynamic lubrication numerical calculation model,a numerical calculation model of linear contact isothermal elastohydrodynamic lubrication considering surface roughness was established.The random surface roughness is used to replace the actual rough surface.The Newton-Raphson method is used to solve the equation numerically.The amplitude and spacing of surface roughness were changed to research their effects on film thickness and pressure.The results show that after changing the amplitude of surface roughness, the film thickness curve and pressure curve fluctuate in the central region.With the increase of surface roughness,the fluctuation degree of them becomes more and more intense,and the local pressure in the pressure fluctuation region is larger. After the surface roughness spacing is doubled,the fluctuation degree of film thickness curve and pressure curve in the fluctuation region is more dense.With the increase of surface roughness,the fluctuation degree of film thickness curve and pressure curve becomes more intense,and the maximum value of film thickness and pressure increases slightly.