Based on optical molecular imaging and the principle of endoscopic imaging,the key technologies and the imaging mechanism of medical endoscope are analyzed.We classify the imaging mechanism of modern medical endoscope into 6 categories,namely white light endoscopy,virtual chromoendoscopy,fluorescence endoscopy,multi-photon endomicroscope,photoacoustic endoscope and optical coherent tomography.Among them,the technique of virtual chromoendoscopy can be further divided as NBI,FICE and i-scan technique.The technique of fluorescent endoscopy includes autofluorescence,non-targeted fluorescent imaging and optical molecular imaging technique.Medical endoscope imaging in the future might utilize multi-modal endoscope,including both white light imaging and optical molecular imaging.Multi-modal endoscope can realize fast surgery localization and real-time analysis,achieving better identification and treatment to cancer tissue with medical endoscope.