Background:Previously,Xiaoyan decoction(XYD)has been found to have a potential anti-tumor effect in vitro.The aim of this study was to explore the effect of XYD in A549 lung carcinoma xenograft mouse model.Method:The A549 lung carcinoma xenograft mouse model were established and divided into control and experiment group.The dynamic growth of the xenograft tumors was observed and the immune cells such as T cell,regulatory T cell(Treg)were explored by Fluorescence-activated cell sorter(FACS)analysis.In this study,network pharmacology was used to screen the anti-cancer monomers in XYD,and their effect targets were also predicted.Result:The result showed that the tumor growth was inhibited and the percent of Treg was down-regulated(P<0.05).Ten drug monomers were screened to inhibit lung cancer cell proliferation and promote cell apoptosis through PI3K/Akt pathway.Conclusion:Our results suggested that XYD inhibited tumor growth and improved the immunity of A549 lung carcinoma xenograft mouse model.