Bupi Yichang Pill uses Radix Codonopsis and Radix Astragali to tonify middle energizer, Radix Aucklandiae to tonify spleen and stomach to stop diarrhea, and Radix Angelicae Sinensis and Radix Paeoniae Alba to replenish blood and generate blood. The combination of these drugs can achieve the functions of strengthening the spleen, promoting bowel movement, stopping diarrhea, regulating the secretion, digestion, absorption and movement functions of gastrointestinal tract, enhancing the body's resistance, preventing secondary infection of intestinal tract and achieving the purpose of preventing diarrhea.