A catheter is required for cervical conization. Cervical conization need to check in which step inside the insertion of catheter? I. Routinely disinfect the vulva, vagina and cervix, and lay a disinfectant towel. Second, vaginal pull hook to expose the cervix, to compound iodine solution coated the entire cervix, clear the scope of the lesion, with rat-tooth forceps clamp cervical iodine does not color area, and gently downward traction. A metal catheter was inserted into the bladder to determine the realm of the inferior border of the bladder. Third, 0.3-0.5cm outside the cervical lesion, use the scalpel to make a circular incision in a vertical direction, tilted inward at 30-40 degrees, and gradually make a conical resection to the deeper part of the cervix. Note that the tip of the cone is directed toward the endocervix, and should not be skewed, so that the cervical tube tissue is intact in a conical shape and cut down. Fourth, cervical molding suture, but not necessarily required.