This paper discusses the restoration of blurred images caused by arbitrary direction constant-speed straight-line movement. Estimating the PSF of a real-world motion-blurred image is an essential step in the restoration process. In the paper, we first prove that we must set two-dimensional point spread function and directly restore blurred image in 2D form, instead of first restore in X direction and then in Y direction. Then we propose the spectral method for estimating the blur range BE and direction of PSE. The DFT image of blurred image contains parallel strips vertical to motion direction. The distance of G(u, v) image center to neighboring black line is reversedly proportional to blur extent BE. Finally, the validity of our PSF estimating method and superiority of windowed Wiener filter over standard Wiener filter is clearly demonstrated in section 4.