Recently a growing interest has been seen in minimally invasive treatments with open configuration magnetic resonance (Open-MR) scanners. Because of the lower magnetic field (0.5T) and various different surgical conditions, sometimes tumors can not be visualized clearly on Open-MR volumes. Combining of CT volumes acquired before surgery, it is possible to identify the tumor's location by application of registration techniques. In this paper, we proposed a non-rigid registration method combined with a semi-automatic liver segmentation method for MR-Guided Liver Cancer Surgery. We first propose a robust method using K-means clustering and graph cut to segment liver from low contrast open MR images and then a free-form deformation based non-rigid registration method is applied to the segmented livers.