The influence of surface roughness in the difficult-to-polished blade regions, such as blade tip, blade fillet and hub, on the aerodynamic performance of the compressor rotor was investigated in order to define the required roughness in these regions for blade polishing. How the roughness in the above-mentioned regions of the rotor affects pressure loss coefficient and outlet total pressure on conditions of 98% choke mass flow in different design speeds was analyzed with the numerical aerodynamic calculation of rotor 37 based on computational fluid dynamics (CFD) tools. The results show that the rotor losses increase with the roughness in the difficult-to-vlished regions of the blade, and the outlet total pressure increases with the roughness of blade tip but decreases with the roughness of blade fillet and hub. The surface roughness value 15 μm is considered as a turning point, because it affects the aerodynamic performance more significantly when it is greater than 15 μm. The aerodynamic performance is most affected by the hub roughness. The hub roughness reduces the rotor losses at 60% of the design speed, but increases the rotor losses at 80%, 100% of the design speed.