There are many kinds of diluents for storing pig liquid semen. Generally, commercial diluent is used, with stable quality, exact effect and convenient use. The dilution powder used to dilute semen should be dissolved 1 hour in advance, so that the pH value is stable and has little influence on sperm. Semen dilution powder can also be dissolved 1 day in advance, and stored in the refrigerator at 4℃ overnight for later use. The water used to dissolve the diluted powder is preferably double distilled water. Modena, a commercial diluent, has a stable effect and is a good diluent. The formula is: glucose (dextrose) 27.5g, sodium citrate 6.9g, sodium bicarbonate 1g, disodium EDTA 2.35g, citric acid 2.9g, dimethylol aminomethane 5.065g and polymyxin sulfate (b).