The semen flowing out may be a normal physiological phenomenon there may also be a disease state. Mainly see the following aspects of the reasons: 1, men in the case of sexual excitement, such as stimulation by the sexes, such as video, pictures, or contact with the opposite sex, there will be fluid flowing out of the penis, but in this case, the fluid flowing out is mainly prostate fluid, sperm content is very small, and basically does not contain sperm, which is the normal reaction of the human body. 2, the normal act of ejaculation, after the penis enters the vagina, through the sex life, will reach the situation of sexual excitement, there will be the act of ejaculation, semen after liquefaction, combined with the egg conception. 3. In some pathological cases, if the patient has impotence and premature ejaculation, the penis just touches the vagina or enters the vagina for less than 1 minute, the ejaculation will occur. In this case, because the semen has not entered the vagina or the distance of the penis into the vagina is not enough, the semen will flow out from the vagina in the case of the penis withdrawing, which will easily lead to infertility. It needs to be treated. 4. If there is no sexual life for a long time and no history of masturbation, semen emission may occur, which is a normal physiological phenomenon, but if there are too many times, timely medical consultation should be sought. In conclusion, there are normal and pathological cases of semen outflow, which should be treated differently, and for pathological cases, early treatment must be given to avoid infertility.