A new type of oil-resistant thermoplastic elastomer of nitrile rubber (NBR) and polyoxymethylene (POM) prepared by dynamic vulcanization were studied. The effects of the curing systems for NBR, acrylonitrile content in NBR, POM content, thermal aging, and reprocessing have on the mechanical properties of NBR/POM thermoplastic elastomers were investigated in detail. NBR/POM thermoplastic elastomers have high tensile strength and excellent oil resistance at elevated temperature. NBR/POM thermoplastic elastomers can be produced in a wide range of hardness. NBRs with higher acrylonitrile content are more suitable for preparing NBR/POM thermoplastic elastomer with high tensile strength and good oil resistance. The NBR/POM thermoplastic elastomer has significantly improved electrical insulation properties compared with NBR (Gessler, M. U.S. Pat. 3,037,959, 1962).