Optical coherence tomography (OCT) endoscope is a new optical imaging technology, which combines OCT with the medical electronic endoscope. With the rapid development of OCT, the endoscopic technology based on OCT becomes a popular research area for its micron level resolution and non-destructive real-time imaging. The basic principles and classification of OCT technology as well as several important parameters of OCT technology including the probing depth, axial resolution and lateral resolution are mainly introduced. Some recent research achievements and development of endoscopic OCT scanning probes are discussed, and the endoscopic OCT scanning probes are compared in terms of outer diameter, scanning speed, axial resolution and lateral resolution. The applications of side-imaging OCT probes in gastrointestinal tract, respiratory tract, blood vessels and other organs as well as the applications of forward-imaging OCT probes in ovaries, breast, brain and other organs are summarized.