Maleation of EPDM in xylene solution using dibenzoyl peroxide as initiator at the boiling point of solution was studied. Effects of amounts of dibenzoyl peroxide and maleic anhydride (MAH), reaction time and temperature, as well as the concentration of EPDM on the bond MAH content of the product were investigated. The results showed that by optimization of the maleation conditions, maleated product with high bond MAH content up to 20 wt % can be obtained without gelation. The maleated EPDM (MEPDM) was utilized in the blending of acetal copolymer and rubber such as EPDM or cis-1,4-polybutadiene. Both the impact strength and the tensile strength of the blends increased when a certain amount of MEPDM was added. Decrease of crystallinity of acetal copolymer in the blends determined by wide angle X-ray diffraction and morphology of the blends examined by scanning electron microscope demonstrated the action of MEPDM as compatibilizer.