Semen examination is an important test to diagnose male infertility. It can reflect the quality of sperm produced by the testes, the patency of the seminal tract and the secretory function of the epididymal glands. Routine semen analysis includes the following: 1. Semen volume: the normal reference range is 2 to 6 ml, less than 2 ml is too little semen and attention should be paid to whether the collection method is correct; more than 6 ml is polyspermia; 2. Appearance: normal semen has a milky white or off-white appearance, the semen ejaculated by those who have not ejaculated for a long time is slightly light and slightly yellowish, and the semen is cool and transparent commonly found in men with no sperm or little spermatozoa. Semen that is brownish red or with blood is called hematosperm, which is commonly found in seminal vesiculitis, prostatitis and other diseases of the reproductive system. 3. pH: The normal pH value of semen is 7,2 to 8,0. When there is an acute infectious disease of the accessory gonads or epididymis, the pH value of semen can be greater than 8,0. When the vas deferens is blocked or the congenital vesicular gland is absent, it can lead to a decrease in the pH value of semen. 4. Liquefaction time: After normal semen is ejaculated, its liquefaction time should be 15-30 minutes; 5. Viscosity: Touch the glass rod to the already liquefied semen and gently lift the rod to form semen filaments, whose length is less than 2cm when normal. 6. Sperm density: Generally expressed by the number of sperm per ml of semen, normal minimum 20×106/ml, sperm density <20×106/ml is oligospermia The density of spermatozoa in the semen is between (5 to 10) × 106/ml for moderate oligospermia; <5 × 106/ml for severe oligospermia; no sperm in the semen for azoospermia. 7, sperm morphology: the percentage of normal form sperm is one of the important indicators to evaluate the fertilization ability of sperm. 8, sperm vitality and motility: recommended sperm vitality classification criteria: sperm vitality is divided into four levels: a, b, c and d. Level a: fast forward motion; level b: slow or sluggish forward motion; level c: non-forward motion; level d: immobility. The normal reference value is greater than 25% for class a or greater than 50% for a+b. The sperm motility rate is the sum of a+b+c grade sperm percentages. 9. morphological analysis: the morphology of the head, body and tail of spermatozoa is observed by staining, which has a greater impact on fertility. the WHO manual of human semen analysis, fifth edition, the normal reference value of sperm morphology is 4%.