In order to solve the problem that the traditional image edge detection techniques only emphasize the horizontal and vertical edges,a new image edge extraction method combining the multi-resolution analysis of nonseparable additive wavelet transformation and the mathematical morphology was proposed. A low-pass filter of nonseparable wavelet was constructed and the source image was decomposed into a low-frequency sub-image and high-frequency sub-images. The low-frequency sub-image was filtered to obtain morphological gradient map. The high-frequency sub-images were added to form an enhanced high-frequency edge map by using modulus maxima value method. Inverse transform of nonseparable additive wavelet transform was performed on the gradient map and edge map and an edge-gradient map was produced. The final edge map was obtained by binarizing the edge-gradient map. The experimental results show that the proposed method has good visual effect. When compared with the traditional image edge detection techniques,it can extract image edges with integrity,multidirection,shift invariance and high speed.