Optical coherence tomography (OCT) is a recently developed imaging technology. With OCT technology one could obtain clear tomography pictures of retina and macula lutea. For the purpose of clinical diagnosis and retina image recognition, a preprocessing technique of retina OCT image has been developed and demonstrated. The edge and contour were extracted automatically through image segmentation and enhancement. It opened the door for the further recognition and analysis of OCT image. Experiments were done on cystoid macular edema, macular hole and normal retina OCT image. The effectiveness of the proposed methods is demonstrated by practical experiments.