Thinning semen may be physiological factors, such as too frequent sex, age, bad habits and so on. It may also be related to varicocele, insufficient secretion of testosterone, radioactive factors, and vasectomy obstruction. The testes produce a low number of sperm, which can easily lead to semen dilution, such as frequent sex or too old. Men with long-term bad habits such as alcoholism, smoking, and staying up late can also lead to impaired sperm production in the testes, causing semen dilution. Varicose veins, insufficient testosterone production, prolonged exposure to radioactivity, and medications can cause testicular spermatogenic dysfunction. If there is obstruction of the vas deferens, it can lead to semen not being discharged out of the body normally, causing semen dilution. Excluding physiological factors, it is necessary to go to the hospital for semen tests in order to clarify the cause of the disease and choose the appropriate treatment plan.