The surface of aero?engine blades has large bending and torsion, and it is difficult to ensure consistent surface roughness during machining. In view of the lack of definitions of measuring position and direction in the current roughness measurement method when measuring blades, which leads to the problem that the measured roughness value cannot determine the eligibility of blade roughness, the research on blade roughness measurement method is carried out. Based on the measured section data of blades, using the roughness probe carried on the CMM, the blade roughness measurement method is obtained by carrying out multi?position and multi?direction roughness measurement experiments on different types of blades and analyzing the difference of the roughness measurement results in different positions and directions. This method associates the blade roughness with the blade profile, and solves the problem that the measurement position and direction of blade roughness are not standardized. The research results are of great significance to accurately and effectively evaluate the qualification of blade surface quality.