Abstract: As an extensively utilized organic synthetic monomer, ε-caprolactone (ε-CL) exhibits notable properties such as biodegradability and biocompatibility. Consequently, the investigation of ε-CL monomer synthesis holds great significance. In this study, a tin catalyst containing magnesium named Sn-Mg-M, was synthesized by a simple method at ambient temperature and atmospheric pressure for the preparation of ɛ-caprolactone monomers. This study focuses on the characterization of catalyst structure using Fourier Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Thermogravimetric analysis (TGA). Furthermore, the catalytic effect of catalyst Sn-Mg-M in Baeyer-Villiger oxidation was investigated to examine the impact of various catalyst ratios, oxidant types, and reaction conditions on the catalytic effect. The experimental results demonstrated that a molar ratio of 4∶1 between Sn and Mg in the catalyst, a feeding molar ratio of 1∶4 between cyclohexanone and hydrogen peroxide (H₂O₂), a cyclohexanone concentration of 0.33 mmol/mL, and a catalyst-to-reactants mass ratio of 1.57∶1, along with a reaction conducted at 65 ℃ for 12 h, resulted in a cyclohexanone conversion rate of 73.27% and a yield of 24.16% for ε-CL. Additionally, it was confirmed that the catalyst exhibited structural stability and could be recycled.