Abstract: A sub-pixel corner detection algorithm based on edge fitting is proposed in this paper,according to the geometric characteristics that a corner must be the intersection of two edges or more.First,image regions that cover the edges forming corners are obtained,and their equations are obtained based on sub-pixel edge detection algorithm in these regions.Second,the coordinates of four intersections formed by two adjacent lines are solved according to the equations.Finally,the subpixel coordinate of the corner are solved by solving the mean of four.By comparing the algorithm proposed by Bouguet,the mean absolute errors of measurement values with this corner detection algorithm are less,when the visual effect and projection error are close,which probe that this algorithm is more suitable for high-accuracy vision measurement.