Sacral block is a part of intralesional anesthesia. It is commonly used for pelvic, lower abdominal or sacral perineal surgery, as well as in the treatment of low back pain or dysmenorrhea. Sacral block is mainly operated in the sacral triangle and sacral foramen. Generally, sacral anesthesia is done by first determining the triangle of the sacral canal and tying in the end of the sacral triangle to connect to the epidural space. The volume of sacral canal is 25-35ml, about 15-20ml of drug injection can play a very perfect effect, while the pelvic or perineal surgery can fully achieve the analgesic and sedative effect, so as to complete the surgery.