The mucous membrane at the entrance to the vagina is torn and bleeding due to external force. It is a severe trauma to the soft tissues between the anus and external genitalia, resulting in a visible laceration of the perineum with localized puffing and thinning, or even severe tearing to the anus. It can be diagnosed by clinical symptoms, vaginal probing, and colposcopy. 1. Abrasion: superficial mucous membrane and skin injury. 2.First degree laceration: skin, subcutaneous tissue and mucous membrane laceration, not involving muscle tissue, depth between 0.2 and 1cm. 3.Second-degree laceration: perineal laceration involving muscle layer and fascia. 4, Ⅲ degree laceration: anal sphincter rupture or combined rectovaginal septum splitting perineal and vaginal laceration is mainly due to the injury of soft birth canal during delivery, the most common one is perineal and vaginal laceration, followed by cervical laceration. Excessive labor force, inadequate dilatation of the birth canal, and inadequate perineal protection and rapid delivery of the fetal head are common causes of laceration. In addition, the labor is too long, the birth canal is edematous under pressure, the extension is reduced; the fetus is huge, the fetal position is not correct, the fetal head passes through the birth canal with a large diameter; surgical assistance, birth canal congenital stenosis, etc. are also factors of birth canal laceration perineal laceration is the most common injury of soft birth canal laceration during labor, it can not only cause more bleeding during labor, but also affect the physiological function and normal life of the mother in serious cases.