A skew angle detection approach using Hough transform was proposed for OMR images. The proposed method doesn’t need to identify exact position of locating marks and can bear high noise. In order to avoid heavy computing of Hough transform, a low-resolution image was created by sampling OMR image. Also, a fast iteration algorithm based on run-length center for written marks segmentation was presented. Experiment results show that the algorithm can achieve skew correction and segmentation of OMR image efficiently and accurately.