Optical coherence tomography (OCT) is a recently developed high resolution biomedical imaging method, allowing for noninvasive visualizing of internal tissue structure and physiology. It is built that a newly developed single-mode fiber-designed OCT system based on Michelson interferometer and optical heterodyne detection using a broadband near-infrared light source. With this developed system elastic light backscattered from the tissue is picked up, and two-dimensional (2-D) and three-dimensional (3-D) OCT images are reconstructed. Fiber-based OCT system is compact, flexible, and convenient to be combined with fiber catheter, endoscope and other imaging equipments to expand its observing scope and application fields.