Methionine sulfoxide reductase B genes (MsrBs) play a crucial role protecting cells from oxidative damage. In this study, we isolated and characterized an MsrB gene from Apis cerana cerana F., designated AccMsrB. The full cDNA of AccMsrB was 757 bp with an open reading frame (ORF) of 414 bp, and the predicted translation product was a 137 amino acid polypeptide with an estimated molecular mass of 15.5 kDa and an isoelectric point of 7.77. Multiple sequence alignment revealed that AccMsrB shares high identity with other known MsrBs (Apis florea F., Apis mellifera L., Apis dorsata F., and Bombus terrestris L.) and contains conservative Cys residues. Quantitative real-time polymerase chain reaction showed AccMsrB to be highly expressed in the epidermis of adult workers, reaching high levels in first-instar larvae, prepupae, and 15-d-old adults. Furthermore, the expression of AccMsrB was upregulated by various oxidative stresses, including 4, 16, 25, and 42°C, ultraviolet light (30mj/cm²), H₂O₂, CdCl₂, HgCl₂, paraquat, imidacloprid, and cyhalothrin. However, AccMsrB was downregulated when exposed to phoxime. These results indicate that AccMsrB might respond to various environmental stresses and protect against reactive oxygen species.