The third and fourth-degree perineal lacerations are a serious complication of vaginal delivery，and because the laceration involves the anal sphincter complex and/or anal mucous membrane，they are referred to as obstetric anal sphincter injuries（OASIS），which is the most common cause of postpartum anal incontinence and severely affects the quality of life. Accurate assessment of the extent of perineal laceration and timely repair of the anatomy after vaginal delivery is essential to restoring sphincter function and improve prognosis. However，some occult OASIS is sometimes missed and cannot be identified in clinical practice. Unrecognized，unrepaired，or poorly healed OASIS can develop into perineal-rectal fistula or rectal-vaginal fistula. It is necessary to strengthen the prevention and management of OASIS，appropriately apply quality management tools，analyze the risk factors and key aspects leading to OASIS，and develop and implement improvement measures from several key points，such as pregnancy and labor management，assisted delivery capacity enhancement，risk assessment，prevention and treatment，in order to reduce or avoid the occurrence of OASIS while improving the ability to identify and repair OASIS.