When women check for abnormalities in the white belt, they are first identified by the color of the white belt, so correspondingly, to check for abnormalities in a man’s semen, the same starts with the semen color. The color of semen can also be used to identify what is wrong with a man’s body. What are the components that determine the color of semen? What is the color of semen when it is abnormal and what causes it? Semen consists of spermatozoa and seminal plasma, of which spermatozoa account for about 10% and the rest is seminal plasma. Spermatozoa are produced by the testicles. Seminal plasma is produced by the prostate, seminal vesicles, urethral bulb glands, paraurethral glands and other accessory gonads, and is mainly composed of water, as well as fat, protein particles, pigment particles, lecithin vesicles, enzymes, fructose and many other components. Semen is a mixture of sperm and seminal plasma, which contains water, fructose, protein and fat, as well as many enzymes and inorganic salts. The color of semen is determined by these components that make up semen. The color of the semen is different from that of the other semen. Generally speaking, normal semen should be translucent and egg-white. The semen of people who have not ejaculated for a long time can be yellowish and sticky. This is a normal phenomenon and is not a cause for concern. In addition, if the semen is yellow in color, it means that the man has inflammation in the reproductive tract and a large number of pus balls are visible under the microscope, most likely caused by septic infection of the prostate and seminal vesicles. Some men may find that their semen turns red or pink or mixed with blood after a certain ejaculation, which often startles them and makes them think they have a terminal illness. In fact, most of this condition is caused by inflammation of the seminal vesicles, a disease with mild symptoms and a good prognosis. Of course, seminal vesicle and prostate diseases can also present hematemesis, but generally speaking, diseased hematemesis is characterized by persistence and gradual aggravation, which is different from the transient hematemesis of inflammation. In addition, tuberculosis, schistosomiasis or systemic hematologic disorders may occasionally cause hematospermia, and all of these conditions should be treated for the appropriate disease. It is clinically proven that when there is bleeding in the genital tract, the semen is red or light red and a large number of red cells are visible under the microscope, some of which appear brownish red or soy sauce colored to the naked eye because of the large number of red cells in the semen. For these pathological hematospermia, the cause should be promptly sought and treated.