Objective Exploring the therapeutic effect of Qingjin Huatan decoction combined with conventional western medicine treatment on phlegm-heat accumulation lung type pneumonia and its impact on its immune function, providing reference for clinical practice. Methods Retrospective analysis was made on the clinical data of 60 cases of phlegm-heat accumulation lung type pneumonia admitted to Huangshan City Hospital of Traditional Chinese Medicine from September 2019 to September 2022. According to different treatment methods, they were divided into the observation group (30 cases were treated with Qingjin Huatan decoction combined with conventional western medicine) and the control group (30 cases were treated with simple conventional western medicine). The treatment effect, inflammatory factor levels [C reactive protein (CRP), procalcitonin (PCT) and interleukin-6 (IL-6)], immune function indicators (CD4+ T lymphocyte percentage, CD8+ T lymphocyte percentage and CD4+ /CD8+ ratio) and occurrence of adverse reactions were compared between the two groups. Results The overall efficacy of the observation group was better than that of the control group (P<0.05). There was no significant difference in the total effective rate between the two groups (P>0.05).After treatment, the serum CRP, PCT, and IL-6 levels were lower in both groups than before treatment, and the observation group was lower than the control group (P<0.05). After treatment, the percentage of CD4+ T lymphocytes and CD4+ / CD8+ ratio in two groups were higher than that before treatment, the percentage of CD8+ T lymphocytes was lower than that before treatment, and the percentage of CD4+ T lymphocytes and CD4+ /CD8+ ratio of patients in the observation group were higher than control group, and the percentage of CD8+ T lymphocytes was lower than that in the control group (P<0.05). There was no significant difference in the incidence of adverse reactions between the two groups (P>0.05). Conclusion The combination of Qingjin Huatan decoction and western medicine has significant therapeutic effect on phlegm-heat accumulation lung type pneumonia, which helps to suppress inflammatory reactions, improve immune function