The existing image edge detection method based on wavelet transform may lose some details of edge and have the drift of the edge position across different scales,under this situation,we present an improved method for edge detection based on wavelet transform.This method smoothes the image first and then detects the image edge.Traditional image smoothing methods avoid the direction of edge and can not retain the image edge efficiently.This paper presents a new image smoothing algorithm based on edge direction.The smoothing algorithm smoothes the image on the direction of edge,and then detects the image edge with this algorithm and wavelet transform.Finally,the experimental results show that the proposed algorithm is very reliable and efficient.