Abstract： Objective： To observe the clinical efficacy of Qinggan Jianpi Sanjie Prescription in the treatment of pediatric chalazion of blended phlegm-damp stagnation type，analyze the gut microbiota characteristics before and after Chinese medicine treatment，and explore the correlation between chalazion and gut microbiota. Methods：A total of 60 children with chalazion of blended phlegm-damp stagnation type treated at Guangdong Women and Children Hospital from January 2023 to March 2025 were randomly divided into the treatment group and the control group using the random number table method， with 30 cases in each group. The treatment group was administered Qinggan Jianpi Sanjie Prescription orally on the basis of conventional western medicine symptomatic treatment， while the control group received conventional western medicine alone. The treatment duration was 14 days. The maximum diameter of the largest cyst and traditional Chinese medicine syndrome scores were recorded before and after treatment， with a six-month follow-up for recurrence. Additionally，13 normal children were recruited as the healthy group. Fecal samples from the treatment group （19 cases） and from the healthy group were collected. DNA was extracted，and 16S rRNA sequencing of gut microbiota was performed using next-generation sequencing to analyze the structural characteristics of the microbiota. Results： After treatment， the total effective rate was 90.00% （27/30） in the treatment group and 66.67%（ 20/30） in the control group，with a statistically significant difference between the two groups（ P＜0.05）. After treatment，the maximum diameter of the largest cyst decreased in both groups compared with that before treatment （P＜ 0.05），and the maximum diameter in the treatment group was smaller than that in the control group （P＜0.05）. After treatment， the traditional Chinese medicine syndrome scores decreased in both groups compared with those before treatment （P＜0.05）. The traditional Chinese medicine syndrome score in the treatment group was lower than that in the control group，but the difference was not statistically significant （P＞0.05）. After six-month follow-up，the recurrence rate was 22.22%（ 6/27） in the treatment group and 45.00%（ 9/20） in the control group，with no statistically significant difference between the two groups （P＞0.05）. In the treatment group， the top three dominant phyla were Firmicutes （40.95% before treatment， 43.90% after treatment）， Bacteroidetes （40.31% before treatment， 39.21% after treatment）， and Actinobacteria （11.90% before treatment， 10.96% after treatment）. In the healthy group， the top three dominant phyla were Firmicutes （34.69%），Bacteroidetes （33.85%），and Proteobacteria （18.38%）. There was no significant difference in Shannon index among the healthy group， the pre-treatment group， and the posttreatment group （P＞0.05）. Beta diversity analysis revealed a significant difference in microbiota structure between the pre-treatment group and the healthy group （P＜0.05）， while no obvious difference was observed between the posttreatment group and the healthy group （P＞0.05）. At the species level， the relative abundance of Bacteroides Facidifaciens was higher in the pre-treatment group than in the healthy group （P＜0.05），and there was no significant difference between the post-treatment group and the healthy group （P＞0.05）. A randomForest plot of the top 30 genera in relative abundance， generated using the R package， showed that Bacteroides ranked first. However， the relative abundance of Bacteroides was not significantly different between the pre-treatment group and the healthy group （P＞ 0.05），but was higher in the post-treatment group than in the healthy group （P＜0.05）. At the genus level，Acetobacter had a very low abundance （nearly undetectable） in the healthy group. The differential genera identified before and after treatment in the treatment group were Alloprevotella and Prevotellaceae_NK3B31_group， but no literature directly linking these genera to chalazion was found. Conclusion： Qinggan Jianpi Sanjie Prescription can reduce the size of chalazion and improve traditional Chinese medicine syndrome manifestations. After treatment， the gut microbial structure of affected children becomes similar to that of healthy individuals. The clinical significance of specific differential genera requires further investigation.