Hysteroscopic myomectomy is the first choice in treating submucous myoma. The successful operation and the treatment effect depend on the type of submucous myoma and the operation skills. The indications for surgery， fibroids in diameter and the myometrial free margin are still controversial issues. The latest view: the myometrial free margin is no longer a limiting factor for hysteroscopic resection of submucous myoma，it is not a static parameter but a dynamic index.