In view of the problems of complicated calculations and blurs edge in image amplification, proposes an image interpolation method based on thinned edge. Firstly applies improved Prewitt operator for the extracted image edge thinning and acquires the precise location of edge, and then interpolates the image differently based on the edge position and non edge position. The experimental results show that this method for image amplification acquires the desired visual effect without obvious aliasing at image edge, and the algorithm is simple and easy to implement.