The horse’s eye is a genital area of the human body that refers to the slit in the middle of the glans of the male penis, which is the opening of the urethra, the common opening for urine and semen. Male urethral opening at the very front of the penis, not only has the function of urination, but also can cause ejaculation due to sexual stimulation, some men can not see their urethral opening, usually gently turn the foreskin can be seen, in the erectile state is also can be clearly seen. The male urethra is generally adult about 18cm, divided into prostate, membrane, spongy part, clinically prostate and membrane part collectively referred to as the anterior urethra, while the spongy part is called the posterior urethra. In daily life, we should pay attention to keep the glans clean, it is recommended to wash the genitals with water every night, avoiding the use of strong acids and alkalis and other irritating liquids, so as not to cause urethral injury.