To analyze the effects of Maxing Shigan Decoction on pulmonary function，microscopic indexes and disease progression in patients with severe pneumonia，and to provide reference for the choice of treatment scheme for severe pneumonia. Methods:A total of 112 cases of severe pneumonia treated in Ninth People's Hospital of Zhengzhou from February 2015 to January 2017 were numbered according to the order of entry，and the odd number was the control group and the even number was the observation group，with 56 cases in each group. The control group was treated with routine therapy of Western medicine，on the basis of which the observation group was treated with Maxing Shigan Decoction. Two groups of patients were treated continuously for 2 weeks as a course of treatment. The pulmonary function indexes before and after treatment were compared between the two groups，including respiratory rate (RR)，forced vital capacity (FVC)，forced breathing volume (FEV1)，arterial oxygen partial pressure (PaO2)，arterial blood carbon dioxide (PaCO2)，maximum exhalation middle segment flow (maMMF)，oxygen index (IO); microscopic indexes，including red blood cell distribution width (RWD)，platelet distribution width (PWD)，high mobility group protein B1 (HMGB1)，tumor necrosis factor-alpha (TNF-alpha)，calcitonin (PCT)，interleukins-6 (IL-6); and condition change index，including APACHE II score，CPIS score，and PIS score. The adverse drug reactions during treatment were compared between the two groups. The outcome of the two groups was compared. Results:1) The APACHE II score，CPIS score and PIS score of the two groups were significantly decreased after the treatment，and the scores of patients in the observation group were significantly lower than those of the control group (P<0.05); 2) RR，FVC，FEV1，maMMF and IO of the two groups were increased after the treatment，and those of the observation group were higher than those of the control group (P<0.05); 3) after the treatment，the RWD，PWD，HMGB1，TNF-α，PCT and IL-6 in the observation group were significantly decreased and were lower than those of the control group (P<0.05); 4) there was no significant difference in the rate of adverse drug reactions in the two groups (P>0.05); 5) The mortality rate in the observation group was 7.14% with 4 cases. The mortality rate in the control group was 12.50% with 7 cases. The mortality in the observation group was significantly lower than that in the control group (P<0.05). Conclusion:Maxing Shigan Decoction in the treatment of severe pneumonia patients combined with Western medicine can reduce the inflammatory state of the patients，improve the immune function，respiratory function，slow down the disease progression，and improve the prognosis of the patients effectively，with high safety and high clinical value.