The invention discloses an endoscopic OCT imaging system adopting an optical path difference external compensation common-path interference probe, comprising a light source, an optical path difference external compensation interferometer, first and second acousto-optic frequency shifters, an optical circulator, and an optical fiber Rotary connector, spiral scanning mechanism, endoscopic probe, glass spacer rod, Green lens, 45° cylindrical mirror, transparent sealing sleeve, metal outer sheath, window, detector, data acquisition card and computer, etc. Use the front surface of the Rigling lens of the endoscopic probe as the reference surface, and the optical path difference between it and the sample is compensated by the optical path difference external compensation interferometer; the spiral traversal scanning method is used to reduce the missed detection of lesions, and the flat window is used to To eliminate the astigmatism usually caused by the cylindrical transparent sealing sleeve, the acousto-optic frequency shifter combined with signal filtering and demodulation technology is used to eliminate the artifacts in the imaging results. The invention has the characteristics of strong anti-interference ability, plug-and-play probe, reduced missed detection of lesions, no false image interference, no astigmatism in incident sample beams, and the like.