Optical coherence tomography (OCT) is a key technology for high-resolution biomedical imaging. Intraoperative handheld endoscopic OCT combines optical fiber communication with endoscopic technology. Based on the principle of low coherence interference, it uses a submillimeter miniaturized handheld probe (diameter≤1 mm) and flexible scanning mechanisms such as MEMS actuation and fiber vibration. Overcoming the penetration depth limitation of traditional OCT, it can obtain micron-level high-resolution structural images such as retinal stratification and vascular intima in turbid media such as blood and tissue fluid. Its clinical application widely covers ophthalmology (real-time navigation of vitreoretinal surgery), cardiology (vascular anastomosis evaluation), neurosurgery (deep brain tissue imaging) and breast tumor resection (microscopic margin assessment), etc. Through the integrated surgical instruments such as lateral or forward scanning probes and OCT surgical forceps, the operation and imaging can be synchronized and the blind area of the visual field can be eliminated. The current technology has challenges in narrow lumen adaptability and multimodal information fusion. The future development will focus on the development of submillimeter flexible probes, artificial intelligence-assisted lesion recognition, robot collaborative navigation, and the popularization of low-cost disposable devices, so as to promote its evolution to an intelligent surgical navigation system. This article briefly describes the current development status of intraoperative handheld endoscopic OCT, reviews its representative works in terms of system structure optimization and clinical application, and presents an outlook for its future development.