The invention discloses a pregnant sow feed capable of preventing diarrhea and a preparation method thereof. The feed is prepared from the following raw materials in parts by weight: 150-180 parts of barley protein powder, 140-160 parts of corn flour, 120-160 parts of wheat bran, 8-12 parts of calystegia sepium hornworm pupa powder, 10-15 parts of sweetpotato hornworm pupa powder, 2-3 parts of kudzu vine radix, 1-2 parts of radix scutellariae, 1-2 parts of rhizoma coptidis, 1-2 parts of radix paeoniae alba, 1-2 parts of prepared rhizome of rehmannia, 0.5-1 parts of garlic, 0.5-1 parts of ginger, 8-15 parts of chicken liver, 7-9 parts of fish meat, 0.5-1 parts of green pepper, 1-2 parts of caraway, 2-3 parts of soybean paste, 0.5-1 parts of vinegar, 10-14 parts of millet, 8-13 parts of sago, 2-4 parts of diced mango, 1-2 parts of grape, 1-3 parts of coptis chinensis leaves, 1-3 parts of fat emulsion, 4-8 parts of diatomite, 5-10 parts of talcum powder, 4-8 parts of medicinal charcoal, 1-2 parts of calcined oyster powder, 1-2 parts of calcined dragon bone powder, 10-15 parts of an attractant and an appropriate amount of water. The feed disclosed by the invention is designed based on special nutritional requirements for the pregnant sow, meanwhile can prevent and control diseases, prevents abortion and stillbirth in the pregnant period for the sow, and further strengthens the resistance of the sow on diseases.