A transcutaneous lumbar intervertebral foramen enlargement and shaping instrument with a nerve monitoring function, at least comprising a plurality of soft tissue expansion tubes (1) incrementally increasing in size, a plurality of expansion sleeves (2) incrementally increasing in size and a plurality of protective sleeves (3) incrementally increasing in size; the soft tissue expansion tubes (1), the expansion sleeves (2) and the protective sleeves (3) all comprise a tube body and an insulated handle (6) disposed on an end of the tube body; the tube bodies all comprise an insulated outer wall and a metal inner wall; a conductive portion (4) having an electrical connection with the metal inner wall and to be electrically connected to a nerve detector is disposed on the insulated outer wall. The shaping instrument has high safety when performing transcutaneous lumbar intervertebral foramen enlargement and shaping, can be used with the nerve detector, further ensuring the operational safety of a surgical procedure.