This study explored the function and mechanism of cytokine-like protein 1 (CYTL1) in regulating the wound-healing process of rats with diabetes mellitus (DM). A wound was made in diabetic rats, in which CYTL1 overexpression or HDAC1 expression-interfering adenovirus was injected. The wound area on day 0, 7, 14 and 21 was observed and photographed to calculate the wound-healing rate. The wound tissues were collected for H&E, Masson staining and CD31 immunohistochemistry. The HDAC1 and CYTL1 mRNA and protein expressions in wound tissues were detected by RT-qPCR and western blot. The regulation of HDAC1 on CYTL1 was predicted by hTFtarget and AnimalTFDB database. The H3K27Ac level in the CYTL1 promoter was detected by chromatin immunoprecipitation (ChIP). Diabetic rats with CYTL1 overexpression or interfered HDAC1 expression had accelerated the wound-healing rate, in which massive fibroblasts, attenuated inflammatory infiltration and increased collagen and microvessel density were observed. Further experiments found that HDAC1 can inhibit CYTL1 transcription and expression by inhibiting H3K27Ac expression in CYTL1 promoter. Collected evidence showed HDAC1 can inhibit CYTL1 transcription by down-regulating the H3K27Ac level in CYTL1 promoter to slow down the wound-healing process in diabetic ulcer rats.