The main reasons for vaginal bleeding after sex are: 1) vaginal wall laceration, inappropriate position or movement during sex, excessive force, etc. leading to vaginal tear, causing bright red bleeding.2) Cervical cancer, bleeding after every sex with foul smell in the vagina is highly suspicious of cervical cancer.3) Cervical polyps, which is the main reason for bleeding after sex, mostly seen in women in their childbearing years, and usually there may be leukorrhea with blood.4) Hymenal tear, bleeding during the first time is related to hymenal laceration.5) Endometriosis, when endometriosis appears as a lesion nodule in the vagina, the endometriosis may be related to the hymenal laceration. 4, hymen tear, bleeding during the first time of sex is related to hymen crack.5, endometriosis, when endometriosis to the vagina lesion nodule, there will be bleeding in the process of sex, accompanied by sex pain bleeding is not much.6, the uterus placed in the birth control ring, take intrauterine device contraceptive women, if the ring is not adapted to the ring, the endometrium will be damaged under the stimulation of the birth control ring. Stimulation of the endometrium will occur under the stimulation of the endometrial damage caused by abnormal bleeding, especially after sex more obvious.