The present surface roughness research is based on machine parts surface cross section profile analysis. But in practical applications machine parts surface roughness behaves as a 3D object. Therefore it is necessary to create a new theoretical and practical basis for machine parts surface assessment as a 3D quantity. This paper contents investigation of 3D surface parameters, characterizing height and spacing of surface roughness irregularities, description of the 3D measurement system and air compressor cylinders surface analysis. It is found that Air Compressor Cylinders surface roughness can be presented by mean arithmetic deviation of surface and mean spacing between peaks in two perpendicular directions of surface. These parameters are relatively convenient for measurement using standard equipment and are easily reproduced in manufac-turing practice.