Abstract： Objective： To observe the clinical effect of modified Daotan Decoction combined with western medicine for Parkinson′s disease （PD） of phlegm-heat and stirring wind type complicated by functional constipation. Methods： Eighty patients with PD of phlegm-heat and stirring wind type complicated by functional constipation admitted to Huzhou TCM Hospital Affiliated to Zhejiang Chinese Medical University from January 2024 to May 2025 were included as the research subjects. They were divided into the control group and the treatment group according to the random number table method，with 40 patients in each group. Both groups received basic treatment for PD，including Mosapride Citrate Tablets. The treatment group was additionally treated with modified Daotan Decoction， and both groups were treated for four weeks. Before and after treatment，the traditional Chinese medicine syndrome scores，the Scale for Outcomes in Parkinson′s Disease-Autonomic（ SCOPA-AUT） scores，and Patient Assessment of Constipation- Quality of Life （PAC-QOL） scores were evaluated， and serum immunoglobulin [immunoglobulin A （IgA）， immunoglobulin M（ IgM），immunoglobulin G（ IgG）] levels，T lymphocyte subsets（ CD3+，CD4+，CD8+） levels，and gut microbiota （Lactobacilli，Bifidobacteria，Enterococci，Escherichia coli） counts were detected. The clinical effects and incidence of adverse reactions during treatment were compared between the two groups. Results：After four weeks of treatment， the total effective rate in the treatment group was higher than that in the control group （P＜0.05）. The traditional Chinese medicine syndrome scores， SCOPA-AUT scores， and PAC-QOL scores in both groups were decreased when compared with those before treatment （P＜0.05）， and the above three scores in the treatment group were lower than those in the control group （P＜0.05）. The levels of IgA and IgG in the treatment group were reduced when compared with those before treatment， and the IgM level was increased when compared with that before treatment（ P＜0.05）. The levels of IgA and IgG in the treatment group were lower than those in the control group，while the IgM level was higher than that in the control group，and the differences were statistically significant（ P＜0.05）. The levels of CD3+ and CD4+ in the treatment group were increased when compared with those before treatment， and the CD8+ level was reduced when compared with that before treatment，differences being significant （P＜0.05）. The levels of CD3+ and CD4+ 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）. The count of Lactobacilli and Bifidobacteria in the two groups was elevated compared with that before treatment， and the count of Enterococci and Escherichia coli was reduced compared with that before treatment， differences being significant （P＜0.05）. The count of Lactobacilli and Bifidobacteria in the treatment group was higher than that in the control group （P＜0.05），and the count of Enterococci and Escherichia coli was lower than that in the control group，differences being significant（ P＜0.05）. During treatment， the incidence of adverse reactions in the treatment group was lower than that in the control group （P＜0.05）. Conclusion：The combination use of modified Daotan Decoction and western medicine can improve the curative effect on PD of phlegm-heat and stirring wind type complicated by functional constipation， which can alleviate the clinical symptoms，improve the autonomic nervous system function，and enhance the quality of life of patients. Its mechanism may be related to the regulation of the systemic immune status， and the correction of intestinal microbiota disorders， with good safety and clinical tolerance.