To explore the protective effect of Huangqin Decoction on ulcerative colitis and related cancers in mice based on network pharmacology.Methods:Adult male C57BL/6 mice(6～8 weeks,18～22 g) were used in the experiment.Under standard environmental conditions at a temperature of 20～25 ℃,the mice were housed in cages in a 12 h light-dark cycle,and had free access to standard food and water.According to the experiment,the mice were randomly divided into control group,induction group,Huangqin Decoction group,tumor induction group,and Huangqin Decoction+tumor group.They were sacrificed on the 11th day for immunohistochemistry and determination of tumor number and size.Dextran sodium sulfate was used to induce ulcerative colitis model in mice.Immunohistochemical analysis was conducted on colon tissue,and myeloperoxidase(MPO) activity was detected to reflect inflammation.Flow cytometry was employed to count white blood cells,and the body weight of the mice was monitored and recorded daily.Results:The body weight and colon length of the induction group were lower and the white blood cell content,spleen index,colon injury score,histological score and MPO activity were higher than those of the control group(all P<0.05).The body weight and colon length of the Huangqintang group were higher and the white blood cell content,spleen index,colon injury score,histological score and MPO activity were lower than those of the induction group(all P<0.05).Compared with the conditions of tumor induction group,the tumor load and size of Huangqin Decoction+tumor group decreased(P<0.05).Conclusion:Network pharmacology indicated Huangqin Decoction had a protective effect on ulcerative colitis,which could inhibit inflammation and tumor development.