Abstract: The weatherresistant polyoxymethylene(POM)compounds were prepared through meltcompounding of dimethylsiloxane,UV absorbers,UV stabilizers,UV shielding agents,antioxidants,and formaldehyde absorber.The retention of mechanical properties of the POM compounds was investigated the light ageing,thermooxidative aging,and hydrothermal aging.The thermal stability of the weatherresistant POM compounds was evaluated by thermogravimetric analysis before and after aging experiments,and the crystalline structures of POM and the additive distribution in matrix were also investigated by polar optical microscopy.The addition of weatherresistant additives significantly increased the retention of mechanical properties of POM.The aging of POM mainly occurred in the amorphous region,and POM was particularly sensitive to light,heat,and oxygen,but less effect to the hot water.Weatherresistant additives were mainly distributed in the amorphous region,and meanwhile,they performed the weatherresistant effect on POM.These weatherresistant additives were also gradually expended during the aging process with the exposure of UV irradiation.