Abstract: To improve the location accuracy of the image further, a precise location subdivision algorithm based on the interpolation theory was designed. A subpixel level measurement is achieved through multiscale wavelet transform combining with cubic spline interpolation. It can not only accurately locate the edge, but also effectively remove the noise and improve the stability and accuracy of edge detection according to the wavelet edge detection methods of multi-scale edge detection. Here, the cubic spline interpolation function is a piecewise interpolation function, algorithm complexity is low, the connection between paragraphs is smooth with fast convergence and stability. The two fused edges location algorithm mentioned above can accurately detect the image with the accuracy of 0.001 pixels.