There are several methods of dilation as follows: 1. metal dilation rod dilation, which is also the most traditional method, starting from the 4th dilation rod, and dilation in sequence, do not dilation in alternate numbers, otherwise it is easy to damage the cervical muscle fibers and cause cervical insufficiency. 2. medication dilation, Misoprostol tablets can be placed in the posterior vaginal fornix 12 hours before surgery, or carpropregnation pessary can be placed in the posterior vaginal fornix 3 hours before surgery. 3. seaweed rod, placed in the posterior vaginal fornix 12 hours before surgery placed into the cervical canal 12 hours before the procedure. While dilation is indicated for abortion, trans-uterine hysteroscopy and therapeutic procedures, the normal endocervical opening is closed and can only pass through a No. 4 dilation rod. For abortion, the opening needs to be dilated to pass through a No. 8-10 dilation rod, and for hysteroscopic treatment, the opening needs to be dilated to pass through a No. 10 dilation rod.