(1) In Denmark, one of the most developed countries in pig raising, most pig farms in the country are fed with liquid feed. Denmark's excellent pig production performance can not be separated from the common use of liquid feed system in Danish pigs. (2) The use of liquid materials is convenient for management and can save labor. (3) Liquid feeding can reduce dust, thus reducing pig lung disease, which is conducive to pig health. (4) It is convenient to add lactic acid bacteria to improve the intestinal flora of pigs, which is beneficial to the intestinal health of pigs, improve the nutrient absorption capacity, and reduce the feed cost. (5) Reduce the risk of producing Salmonella and reduce the incidence of Escherichia coli. (6) Some problems of dry feeding are avoided, such as the granulation cost of dry feeding, pigs do not eat powdered materials due to partial pulverization of granular materials, mildew caused by dead corners of corner wheels, and mildew caused by dust in dry ration barrels. (7) Liquid feed focuses on the matching between the nutrition contained in the feed and the nutrition required by the pigs, not necessarily the amount of corn, soybean meal, fish meal, From the perspective of the nutritional components required by the pigs, we can detect the nutritional components of various feed raw materials, prepare the nutritional liquid feed required by the pigs at all stages, and make use of the local advantageous feed raw materials (such as distiller's grain, bean curd residue, alfalfa powder, cassava, expired human food, etc.), so as to save feed costs and improve the efficiency of pig breeding. (8) Automatic feed distribution control, precise feeding, control the appropriate amount of feed, pigs have enough nutrition without waste, save feed costs, and bring economic benefits. (9) Higher feed intake and growth rate, so as to shorten the marketing time. (10) To improve the feed conversion rate, according to the summary of Danish data, fattening pigs from 30kg to 110kg can save 13.6kg feed.