Background. Negative pressure wound therapy (NPWT) with instillation (NPWTi) is a new treatment for chronic skin ulcers (CSUs), but the choice of perfusate is still investigated. The clinical application of Huoxue Shengji (HXSJ) decoction has been proved to promote the formation of granulation. The formation of fresh granulation, angiogenesis, and proliferation of vascular endothelial cells are closely related. The purpose of this study was to observe the clinical efficacy of NWPT with HXSJ decoction instillation in the treatment of CSUs and to explore the potential mechanism by which HXSJ decoction promotes proliferation of vascular endothelial cells at the cellular level. Methods. In the clinical study, the random number table was used to divide the patients into three groups (patients were numbered by visit time and assigned a random number and grouped by the remainder after the random number was divided by 3, and when the number of patients in one group reached 20, the enrolment of this group is stopped), including NPWT combined with HXSJ decoction instillation (group A), NPWT combined with normal saline instillation (group B), and NPWT (group C). Related indexes were examined, including the wound cavity volume, bacterial culture, histopathology examination, time periods of debridement, repair methods, and the time of ulcer healing. In the basic research, the effect of HXSJ decoction on the proliferation of HUVECs was analysed by CCK-8 assay and RT-PCR and western blot were used to quantify the VEGF and VEGFR-2 expression in the relevant signalling pathway. Results. There was no significant difference in the improvement rate of invasive cavity volume ( P > 0.05 ) between groups A and B, but a significant difference was observed between groups A and C ( P < 0.05 ). There was no significant difference in microbial reduction among groups (all P > 0.05 ). Histopathological examination showed that the microvascular count in group A was significantly higher than that in groups B and C (both P < 0.01 ) and there was no statistical difference between groups B and C ( P > 0.05 ). There were no significant differences in the number of invasive lesions and repair methods among the groups (all P > 0.05 ). The healing time of group A was significantly faster than those of groups B and C (compared to group B, P < 0.05 ; compared to group C, P < 0.01 ), and there was no statistical difference between groups B and C ( P > 0.05 ). In the cellular experiments, concentration screening was performed and 125 μg/mL HXSJ decoction showed the most significant effect on the proliferation of HUVECs and also enhanced the expression of VEGF and VEGFR-2. Conclusion. HXSJ decoction can enhance the expression of VEGF and VEGFR-2 and promote the proliferation of HUVECs. Treatment with NWPT with HXSJ decoction instillation can further reduce the wound cavity volume; meanwhile, it can promote blood vessel formation in ulcer wounds, thus accelerating the healing of CSUs.