Abstract: In this research, silicone rubber powder and nano-vulcanized styrene butadiene rubber (SBR) were selected to toughen the domestic polyoxymethylene copolymer (POM). By the universal tensile tester, thermogravimetric analysis, differential scanning calorimetry, polarizing microscope, X-ray diffraction and scanning electron microscopy, the crystallization behavior and mechanical properties of the modified polyoxymethylene were analyzed and researched. It was shown that the optimum amount of silicone rubber was 3% of the total mass and the optimum amount of nano-vulcanized SBR is 1% of the total mass; the toughening agent can be refined crystal of POM; the impact resistance of the modified POM was improved more than 30% while the tensile strength of it was almost no decline.