Deep eutectic solvents (DESs) were prepared by mixing a quaternary salt as a hydrogen bond acceptor with a hydrogen bond donor. In this study, DESs had an excellent effect as a solvent-catalyst for the esterification of palmitic acid and methanol. This method was found to be safe, mild, simple, and eco-friendly. A range of DESs with different mixing ratios were used to optimize the preparation of methyl palmitate. Other factors, such as temperature, time and DESs/methanol ratio, were also examined. The optimal DES was prepared from tetrabutyl ammonium chloride and acetic acid (1 : 2); the methanol and palmitic acid sample to DES ratio was 1 : 0.5 (v/v). The reaction was optimized at a methanol/palmitic acid ratio of 10 : 1 (mol/mol) at 60 ℃ for 60 min. The yield was 94.3% under the optimized conditions. Therefore, DESs can be developed as a catalyst for the esterification of palmitic acid for obtaining methyl palmitate as biodiesel, and have potential applicability in other biodiesel pretreatments.