The high-accuracy measurement of complex airfoil surfaces is a critical issue in the inspection of blades. Aiming at this problem, a compound measuring principle is proposed in this paper. Using the principle, the airfoil surface and root datum of a blade are measured based on contact inductance method and non-contact laser triangular method, respectively. And a four-coordinate measuring system is designed and established. Then, on the basis of the mechanical structure of the measuring system, the geometric error of which is analyzed syste-matically. And a corresponding extraction and compensation method is proposed based on the laser interferometry. The experimental results show that the proposed error analysis and compensation methods can improve the accuracy of the four-coordinate measuring system effectively.