A high-precision positioning method was proposed to meet the demands for automatic positioning in complex backgrounds. First, sub-pixel edge sequences are derived from discrete edge points of a preprocessed image by applying an edge tracing algorithm and interpolation algorithm. Next, the non-circular edges were excluded by salient point segmentation and center constraints based on geometric features. Then arcs belonging to the same circle are reorganized by more efficient relative position constraints and inscribed triangle constraints. And finally the arc segment group was subjected to least squares fitting to achieve accurate positioning of the target center. In this paper, by extracting sub-pixel arc sequence and a more efficient arc recombination method, the positioning accuracy is improved and the time of arc recombination is reduced. The experimental results demonstrate that the positioning accuracy of the simulated image reaches 0.007 pixel, and the accuracy of the dynamic displacement experiment reaches 0.05 mm, which can meet the needs of visual measurement real-time positioning under adverse conditions such as illumination changes, noise, and occlusion.