Abstract：Objective：To observe the clinical effect of Jiebei mixture combined with methylprednisolone for severe pneumonia， and its effect on T lymphocyte subsets， partial pressure of blood oxygen and oxygenation indexes. Methods：A total of 100 cases of patients with severe pneumonia were selected and divided into the control group and the treatment group according to the random number table method，with 50 cases in each group. The control group was treated with methylprednisolone sodium succinate for injection，and the treatment group was additionally treated with Jiebei mixture based on the treatment of the control group. Both groups were treated for fourteen days. The T lymphocyte subsets，partial pressure of blood oxygen and oxygenation indexes before and after treatment as well as the clinical effects， the improvement time for symptoms and the hospitalization time in the two groups were compared. Results： The total effective rate was 96.00% in the treatment group，higher than that of 78.00% in the control group (P＜0.05). The time of defervescence， relieving cough and disappearance of lung shadow as well as the hospitalization time in the treatment group were shorter than those in the control group(P＜0.05). After treatment，the partial pressure of blood oxygen and oxygenation indexes in the two groups were increased when compared with those before treatment(P＜0.05)，and the blood oxygen and oxygenation indexes in the treatment group were higher than those in the control group(P＜0.05). After treatment， the levels of CD3+ and CD4+ and the values of CD4+/CD8+ in the two groups were increased when compared with those before treatment(P＜0.05)，and the CD8+ level was decreased(P＜0.05)；the levels of CD3+ and CD4+ and the value of CD4+/CD8+ in the treatment group were higher than those in the control group(P＜0.05)，and the CD8 + level was lower(P＜0.05). Conclusion： Jiebei mixture combined with methylprednisolone for severe pneumonia can effectively improve clinical symptoms，respiration and immune function.