Objective:To investigate the regulatory role of RNA m 6A methyltransferase (METTL14) in ultraviolet B (UVB) radiation-induced skin injury, and to preliminarily explore the potential of targeted inhibition of METTL14 for treating UVB-induced skin injury. Methods:A UVB radiation-induced skin injury model was established by exposing C57BL/6J mice to 150 mJ/cm 2 UVB, and was assessed and scored with HE staining and Masson staining. UVB radiation-induced cell injury models were established by exposing human immortalized keratinocytes (HaCaT) and human skin fibroblasts (WS1) to 10 and 30 mJ/cm 2 UVB, respectively. The m 6A levels in the mouse skin and cell models after UVB exposure were quantified by colorimetric assay, and m 6A-related enzymes in cells were measured by Western blot. HaCaT and WS1 cell lines overexpressing METTL14 were constructed using recombinant adenoviral vectors, and the overexpression effects were tested by Western blot. The METTL14 overexpression cells were examined for their m 6A levels, proliferative abilities after UVB exposure (by clone formation assay), and changes in apoptosis (by flow cytometry). The model mice with UVB-induced skin injury in the treatment groups received subcutaneous injection of the METTL14 inhibitor S-adenosylhomocysteine (SAH) solution (1 mg/kg, 5 mg/kg) twice consecutively before and after irradiation; and the mice were assessed and scored for skin injury with HE staining and Masson staining. Results:On the 4th day after 150 mJ/cm 2 UVB irradiation, the mice showed remarkable skin injury, pathologically featuring inflammatory infiltration, tissue structure disorganization, and collagen fiber degradation, reaching the maximum score; and the m 6A level in the skin was significantly downregulated ( t = 3.07, P < 0.05). At 24 h after 10 and 30 mJ/cm 2 irradiation, HaCaT and WS1 cells showed significantly reduced survival rates ( t = 7.64, 7.15, P < 0.05), significantly downregulated m 6A levels ( t = 4.78, 4.36, P <0.05), and significantly time-dependent downregulation of METTL14 protein expression ( t = 6.39, 4.76, P < 0.05). In HaCaT and WS1 cells, METTL14 overexpression significantly up-regulated m 6A levels ( t = 7.66, 3.67, P < 0.05), significantly inhibited the clone-forming ability of cells after UVB irradiation ( t = 6.29, 3.84, P < 0.05), and significantly increased the rate of cell apoptosis ( t = 3.48, 9.54, P < 0.05). Compared with those in the normal saline group, the model mice with UVB-induced skin injury in the SAH treatment group (5 mg/kg) showed significantly decreased pathological scores of skin injury ( t = 3.21, 4.27, 5.81, P < 0.05), with milder inflammatory infiltration, more orderly tissue structure, and less collagen fiber degradation. Conclusions:METTL14 can increase the sensitivity of skin cells to UVB radiation, and targeted inhibition of METTL14 can effectively alleviate UVB radiation-induced skin injury, which may be a potential new target for the treatment of UVB radiation-induced skin injury.