Objective To investigate the effect of exosomes ( Exos) derived from rat epidermal stem cells (EPSC) overexpressing microRNA-26a (miR-26a) on wound healing in rats with deep second-degree burns. Methods Rat EPSCs were cultured in vitro and transfected with lentiviral particles carrying miR-26a-green fluorescent protein (GFP) and negative control (NC-GFP) to up-regulate the expression of miR-26a. Exos were separated from untransfected, NCGFP-transfected, NC-GFP-transfected and miR-26a-GFP-transfected EPSCs. Transmission electron microscopy and nanoparticle tracking analysis were performed to observe the shape and size of the Exos. Western blot was performed to measure the expression of Exo surface markers CD9, CD63 and CD81. Real-time fluorescent quantitative PCR was performed to measure the expression of miR-26a in EPSC and EPSC-Exos, and the CCK-8 method was applied to measure the proliferation activity of EPSC. A tubule formation experiment was performed to evaluate the effect of miR-26a-EPSCExos on angiogenesis. A rat model of deep second-degree burns was established and separated into control, NC-EPSCExos, and miR-26a-EPSC-Exos groups, with 30 rats in each group. The NC-EPSC-Exos and miR-26a-EPSC-Exos groups ，were given corresponding Exos intervention, and the control group was given an equal volume of PBS once a week for 3 weeks. On the 7th, 14th and 21st days after rats were burnt, the burn wound conditions of the rats in each group were observed and the wound healing rate was calculated. HE stainning was performed to observe histopathological changes of the wounds, and histological scores were obtained. An immunohistochemical method was employed to measure the positive expression of CD31 on the wound and calculate the microvessel density. Results miR-26a transfection significantly increased the expression of miR-26a in EPSC and its Exos and promoted the proliferation of EPSCs ( P< 0. 05 ). Transmission electron microscopy and nanoparticle tracking analysis result showed that Exos were spherical, with a diameter ranging from 40 nm to 150 nm, and positive for CD9, CD63, and CD81. The tubule formation experiments showed that miR-26a-EPSC-Exos was able to significantly increase the tube length and promote endothelial cell angiogenesis ( P<0. 05). The result of the in vivo experiments showed that miR-26a-EPSC-Exos significantly accelerated wound healing and repair in rats with deep second-degree burns and increased the histological score and microvessel density ( P< 0. 05). Conclusions EPSC-Exos overexpressing miR-26a can promote wound healing in rats with deep second-degree burns.