For the partial motion blur caused by motion object in static background, the corresponding relationship among the object velocity, motion blur length, object range and camera parameter such as exposure time is built. A novel algorithm of parameter identification for partial motion blur is proposed. The information of target motion direction is given by Fourier spectrum and Radon transformation, and then the motion direction is adjusted to horizontal direction. Through the image segmentation and binarization, edge detection using the reconstructive Prewitt operator and self-correlation each row in the region of edge image corresponding to the binary image, the motion blur length is given by the statistical information. Moreover, the object velocity is measured. The experimental results show that our method is effective even though the object shape is complex. Between the estimated object velocity and the real average velocity, the experiment errors are all less than 7%. In addition, our method is propitious to auto completion, and has a good real-time performance.