Circular coding target has been widely used in the field of three-dimensional measurement. The center extraction accuracy of the target directly affects the measurement accuracy of the system. Aiming at the problem that the center extraction accuracy of the circular coded target is easily affected by camera angle, a method for extracting the center of the circular coded target based on radial straight line fitting of circular coding is proposed in this paper. First, the radial straight line edge of the circular coded target ring is obtained by edge extraction after image preprocessing, and sub-pixel location of the edge point is achieved by Gaussian fitting. Then, the extracted sub-pixel edge point set is mapped to a parameter space into curves, and the intersection points between these curves is thus obtained. Finally, a random sampling consistency algorithm is used to fit and map to the original coordinate space to get the center coordinate. Simulation results show that the center coordinate error extracted by this method is reduced from 1 pixel to 0.05 pixel with increase of target size and shooting angle. Experimental measurements show that the error of the center coordinate extracted by this method is kept within 1 pixel for different target sizes and shooting angles. Compared with the ellipse fitting method, the reprojection error of the camera calibration is reduced by 20%, and the calibration result is more accurate.