Abstract：Objective：To observe the effect of modified Qingfei Huaji Prescription on acute exacerbation of chronic obstructive pulmonary disease (AECOPD) of phlegm-heat congesting the lung type. Methods：A total of 60 AECOPD patients of phlegm-heat congesting the lung type were divided into the treatment group and the control group according to the random number table method，with 30 cases in each group. The control group was given conventional treatment with western medicines (mainly for anti-infection and relieving cough and asthma，and using hormones if necessary)，and the treatment group was additionally given modified Qingfei Huaji Prescription on the basis of the treatment of the control group. Both groups were treated for seven days. The traditional Chinese medicine (TCM) syndrome scores， the scores of chronic obstructive pulmonary disease Assessment Test (CAT)，and the levels of lymphocyte subsets and inflammatory indicators were compared between the two groups. The correlation between composition and species differences of intestinal flora and flora species and T lymphocyte subsets in the two groups were analyzed. Results： After treatment， the TCM syndrome scores and CAT scores in the two groups were reduced when compared with those before treatment，and the TCM syndrome scores and CAT scores in the treatment group were lower than those in the control group， differences being significant (P＜0.05). After treatment，the levels of CD4+ and natural killer cells (NK cells) and CD4+/CD8+ value in the treatment group were higher than those in the control group， and the CD8+ level was lower than that in the control group， differences being significant (P＜0.05). After treatment， the levels of C-reactive protein (CRP) in the two groups and the level of procalcitonin (PCT) in the control group were respectively down-regulated when compared with those before treatment， differences being significant (P＜0.05). There were no significant differences being found in the comparison of the white blood cell count (WBC) before and after treatment in the same group， and in the comparisons of levels of WBC， PCT and CRP after treatment between the two groups (P＞0.05). In terms of intestinal flora，there were some differences between the two groups from phylum to species. There was a positive correlation between lactobacillus and CD4+，CD4+/ CD8+ and NK cells (P＜0.05)， there was a positive correlation between veillonella and NK cells (P＜0.05)， there was a positive correlation between faecali bacterium and CD4+ and CD4+/CD8+ (P＜0.05)，there was a positive correlation between lactobacillaceae and CD4+ (P＜0.05)， and there was a negative correlation between streptococcus and CD8+ (P＜0.05). Conclusion： Modified Qingfei Huaji Prescription can improve the clinical symptoms and immunity of AECOPD patients of phlegm-heat congesting the lung type， and regulate the intestinal flora.