Restoration of motion blurred images has practical significance in astronomy, military affairs, industrial control, road monitoring and criminal investigation. Estimation of PSF (Point Spread Function) is a key and difficulty in the study for restoration of motion blurred images. This paper carried out Fourier transform for motion blurred images to obtain a frequency spectrum diagram with bright and dark stripes. Based on the direction of bright stripes and the principle that the motion blur direction is vertical, the direction of the bright stripes in the frequency spectrum diagram could be obtained through Radon transform, thus the motion blur direction in PSF could be obtained. The cross-shaped bright line in the frequency spectrum diagram of blurred image could directly affect the accuracy of the experiment results. This paper analyzed the cause of the cross-shaped bright line, and put forward a simple and effective algorithm to remove the interference of the cross-shaped bright line. The experimental results indicate that the proposed algorithm is simple and effective, and it could accurately determine the blur direction through measurement with the error less than 1°.