In order to investigate the effect of Xiaoxianxiong decoction on lipidemia and immune function of hyperlipidemia (HLP) mice and the underlying mechanism, 36 C57BL/6 mice were fed with high-fat diet for 8 weeks to establish the HLP model. The mice were randomly divided into control, model, Xiaoxianxiong decoction low-dose (0.03g/mL), medium-dose (0.06g/mL), high-dose (0.12g/mL) and positive control (2.5 mg/kg lovastatin) groups, with 6 mice per group. After mice sacrifice, the liver and spleen were weighed, and the liver index and spleen index were calculated. The levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HDL-C) in the mice serum were measured by automatic biochemical analyzer. The proportion of CD40⁺/CD40L⁺ cell and Th1, Th2 were detected by FACS, and serum CRP expression was detected by ELISA. The results showed that compared with the control group, the liver and spleen index of the model group increased (all P＜0.05); The levels of CRP, TC, TG, and LDL-C increased (all P＜0.05), and the level of HDL-C decreased (P＜0.05); The percentages of CD40+/CD40L+ cell and Th1 increased and the proportion of Th2 decreased (all P＜0.05). Compared with the model group, the mice liver and spleen index in the middle-dose and high-dose groups were decreased (all P＜0.05); The levels of CRP, TC, TG, and LDL-C were decreased (all P＜0.05), while the level of HDL-C was increased (P＜0.05); The percentages of CD40⁺/CD40L⁺cell and Th1 were decreased, and theTh2 percentages were increased (all P＜0.05). Therefore, Xiaoxianxiong decoction can reduce the blood lipid levels in HLP mice, reduce the degree of inflammation and improve the immune function.