Abstract: OBJECTIVE To observe the effects of different doses of Huangqi on immune function and platelet activating factor in patients with sepsis， and to explore the mechanism of Huangqi in improving immune status of sepsis patients. METHODS 60 patients with sepsis admitted to the Department of Severe Medicine， Wuxi Affiliated Hospital of Nanjing University of Chinese Medicine were randomly divided into three groups: conventional treatment group (20 cases， conventional western medicine treatment)， small dose of Huangqi group (20 cases， 1.5 g of Huangqi granules added on the basis of conventional western medicine treatment， once a day)， medium dose of Huangqi group (20 cases， 3.0 g of Huangqi granules added on the basis of conventional western medicine treatment， once a day)， 5 d a course. The Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) score， sequential organ failure score (SOFA)， peripheral blood lymphocyte subsets， platelet activating factor (PAF) level and 28-day mortality of the three groups before and after treatment were compared. RESULTS The number of total T cells， T helper lymphocyte， CD4⁺/CD8⁺， and B lymphocyte increased after treatment in different doses of Huangqi group (P<0.05， P<0.01)， while T-suppressed lymphocyte and NK cell decreased (P<0.05， P<0.01)， the curative effect was better than that in conventional treatment group (P<0.05)， and the difference was more significant in middle dosage group than small dosage group (P<0.05). The levels of PAF in the three groups decreased after treatment with statistical significance (P<0.05)， while those in the Huangqi groups were better than those in the conventional group (P<0.05). The decrease of PAF in the middle dose group was more obvious than that in the small dose group， and the difference was statistically significant (P<0.05). The APACHE Ⅱ score and SOFA score of the three groups were significantly lower than those before treatment (P<0.05)， while the Huangqi groups were better than the conventional group (P<0.05). The 28-day mortality rate in the middle dose and small dose groups were lower than that in the conventional group， and the difference was significant (P<0.05) but there was no difference between the two groups (P>0.05). CONCLUSION Huangqi granules can improve immune system and mortality of sepsis patients in a dose-dependent manner. Its mechanism may be accomplished by regulating PAF.