The invention discloses combined medicine for treating pig diarrheal diseases. The combined medicine is prepared from the following medicine including quinolones, 654-2 injection, frusemide injection and proxiphylline injection. The quinolone antibacterial medicine and other medicine are used in a matched way; the dosage of the antibacterial medicine is reduced; no antibiotic medicine is contained; a good curative effect is achieved on various kinds of irritable diarrhea and viral diarrhea; particularly, the effect on winter diarrhea and diarrhea with yellow green loose stools is very obvious; the intestinal mucosa can be protected and repaired; the digestive absorption capability of piglets is recovered; the diarrheal diseases caused by various reasons can be effectively treated; the treatment effect is obvious; pigs can be cured generally after 2 to 3 days; the death rate is obviously reduced; good economic benefits are realized.