OBJECTIVE： To study the effects of Yupingfeng powder on immune function of rats with lung-qi deficiency syndrome. METHODS： 60 SD rats were randomly divided into normal group， model group， positive group [Renshen beiqi tablet 0.6 g （crude drug）/kg] and Yupingfeng powder high-dose， medium-dose and low-dose groups [24， 12， 6 g （crude drug）/kg]， with 10 rats in each group. Except for normal group， those groups were given SO2+comprehensive cold stimulation to induce lung-qi deficiency syndrome model. After modeling， treatment groups were given relevant drug solutions intragastrically， and normal group and model group were given constant volume of normal saline intragastrically， once a day， for consecutive 13 d. After administration， serum levels of IL-3 and IL-6， the proportion of CD3+， CD4+， CD8+ in T lymphocyte were determined， and pathological changes of lung and bronchus were observed. RESULTS： Compared with normal group， serum levels of IL-3 and IL-6 and the proportion of CD8+ in T lymphocyte increased significantly in model group， while the proportions of CD3+ and CD4+ in T lymphocyte and the ratio of CD4+/CD8+ decreased （P＜0.01）； obvious lung and bronchus injury and inflammatory reaction were observed. Compared with model group， serum level of IL-3 decreased significantly in positive group and Yupingfeng powder high-dose group； serum level of IL-6 and the proportion of CD8+ in T lymphocyte decreased significantly in positive group and Yupingfeng powder high-dose and medium-dose groups， while the proportion of CD3+ in T lymphocyte increased significantly； the proportion of CD4+ and the ratio of CD4+/CD8+ increased significantly in treatment groups （P＜0.05 or P＜0.01）； lung and bronchial injury， and inflammation reaction were relieved. CONCLUSIONS： Yupingfeng powder can enhance immune function of rats with lung-qi deficiency syndrome.