A new edge detection method based on the fusion of soft morphology and Sobel operator is developed. The omnidirectional morphological elements are designed to do recursive soft morphological operation to enhance operation speed and then delete noise. The rule of fusing the edge obtained by morphology and the edge obtained by Sobel operator is established. And the experimental results show that the clear and continuous edge can be got. This method has good robust to noise and can get reliable edge in noisy image.