Objective To investigate the clinical efficacy of Zhangpi ointment in the treatment of chronic venous leg ulcers （CVLU） and its impact on the microecology of the wound surface by using 16S ribosomal RNA （16S rRNA） high-throughput sequencing. Methods A total of 35 patients with CVLU were divided into a Zhangpi ointment group （treatment group，18 cases） and a control group （17 cases） based on the treatment method. The treatment group was treated with Zhangpi ointment， while the control group received conventional treatment. The treatment course was 4 weeks. The clinical efficacy， wound granulation tissue growth， and changes in the microbial flora were observed. Additionally， the differences in dominant bacterial genera and the correlation with clinical symptoms were analyzed. Results At 28 days post-treatment， the total effective rate of the treatment group was 88.9% （16/18）， and that of the control group was 70.6% （12/17）. The coverage of granulation tissue in the treatment group was significantly higher than that in the control group （P<0.05）. High-throughput sequencing of the 16S rRNA of the wound microbiota showed that compared with before treatment and the control group， the Alpha diversity index in the treatment group decreased significantly after treatment （P<0.05）， and the abundance

of the Proteobacteria phylum and Pseudomonas genus decreased significantly （P<0.05）. LEfSe analysis indicated that the  differences in bacterial genera before and after treatment mainly included Pseudomonas and diminuta（P<0.05）. Correlation analysis revealed that the abundance of Pseudomonas was positively correlated with the clinical PUSH score （r=0.467，P< 0.01）， but negatively correlated with the coverage of granulation tissue （r=-0.545，P<0.01）. Conclusion Zhangpi ointment can ameliorate the clinical symptoms of patients with CVLU and promote the growth of granulation tissue on the wound surface. It may exert its effect by regulating the wound surface microbiota and has a significant inhibitory effect on Pseudomonas of the Proteobacteria phylum.

Zhangpi ointment, Chronic venous leg ulcers, Microecology, Pseudomonas