In view of the traditional need to calculate the curvature and the insufficient threshold selection of detection algorithm angular profile curve, this study proposes an angle detection analytic algorithm based on Freeman code by first edge detection, contour extraction to give Freeman code profile. When the chain code changes, it analyzes whether the chain code of a number of points before and after it is consistent with certain rules to determine the corner point, without the need of traditional corner threshold selection, curvature calculation and other steps. Compared with He & Yung, CPDA, Fast-CPDA, and ARCSS corner detector, the experimental results show that the proposed algorithm has the highest accuracy (ACU) in detecting the corner. The transformation experiments show that the average repetition (AR) is the highest, which shows that the proposed algorithm has good corner detection performance.