An improved methodology is presented in the paper to solve the problem of image edge blurring which exists in conventional bilinear interpolation.The first step is to determine the edge direction and gray gradient direction of the interpolated points according to their geometric position and the gray levels of their adjacent points.Then bilinear interpolation is made along the edge directions.This method can realize interpolation along any edge directions and the algorithm is simple and fast.Experiment shows that the novel method can obviously improve the image quality.