Microendoscopic Discectomy (MED) is a lumbar endoscopic surgery via the posterior laminar space, which is characterized by a working channel of 16-18 cm in diameter through which the entire operation is performed with the aid of an endoscope. The direct translation should be microendoscope or microendoscope, but after entering China, it was translated as intervertebral discoscope, spinal canaloscope, spinal mirror and so on. In 1995, Smith and Foley first introduced the MED technology, then the technology was adopted by the U.S. SOFAMOR DANK company, they launched the first generation of MED system in 1996, and in 1999, the U.S. SOFAMOR DANEK company launched the second generation of MED equipment after improvement, that is, METRx system, its microscopic field of view magnification from the first generation The field of view magnification from the first generation of 15 times to 64 times, the clinical application effect is more satisfactory. At present, the MED system has been localized. Posterior microendoscopic lumbar discectomy is fundamentally different from the previous percutaneous endoscopy. It is a minimally invasive and endoscopic version of the traditional open disc removal technique combined with endoscopic technology, which can clearly display the surgical field on the monitor, with special surgical instruments, small incision, small peeling tissue area, less bleeding, less destruction of normal tissues, and direct visualization of the dural The endoscope can be used to remove the nucleus pulposus of the lumbar intervertebral disc and clean the nerve root channel, so it is suitable for most types of lumbar disc herniation. Nowadays, with the improvement of surgeons’ operation level, the indications for MED are similar to those of conventional open surgery. Indications for MED: (1) lumbar disc herniation with predominantly radicular pain; (2) very lateral type of lumbar disc herniation; (3) postoperative recurrence of the original segment contralateral to the original segment; (4) single-segment lateral saphenous stenosis and/or nerve root canal stenosis; (5) decompression of spinal stenosis; (6) bilateral decompression of unilateral access to spinal stenosis; (7) intervertebral fusion and percutaneous internal fixation after decompression.The advantage of MED is minimally invasive, allowing intraoperative visualization of the anatomical structures and the ability to remove the laminae, articular processes, osteophytes, calcified ligaments, and herniated disc tissue. In this sense, it is difficult to suggest absolute contraindications, and all disc surgeries completed clinically by open surgery can be completed by MED.