In order to explore the influence of surface roughness,surface waviness and both on the lubrication performance of gas slider bearing,by using the fractal function to characterize the rough surface and the sinusoidal curve to characterize the surface waviness,then substituting the Reynolds equation of ultra-thin gas film lubrication suitable for any Knudsen number,the lubrication equation considering the surface morphology characteristics and thinning effect was obtained and solved by the finite difference method.The results show that in case of no contact between bearing surfaces,the greater the bearing surface roughness,the higher the gas film pressure and the higher the bearing bearing capacity.The amplitude,phase angle,and period of the waviness have a significant impact on the bearing performance.The bearing capacity is large when the phase angle is near 3π/4 and the period is near 0.4 and 0.8.For the composite rough surface,the surface roughness can make up for the possible loss of gas film pressure and bearing capacity caused by surface waviness,and the larger the bearing number,the more obvious the effect.The surface roughness has little influence on the pressure center,while the waviness has a great influence on the pressure center.