Abstract: The effects of artificial weathering on the chemical structure, surface topography and mechanical properties of ethylenepropylene-diene monomer (EPDM) were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), computer-controlled testing machine and spectrophotometer. The results showed that an oxidation layer formed after 90 d of exposure. XPS results confirmed the production of C-O-C/C-OH, C=O and O-C=O groups. With prolonging exposure time, the crosslink density increased linearly, the surface of EPDM turned to redder, more yellow and lighter. Little voids and micro cracks were formed under exposure to artificial weathering environment. The tensile strength, tear strength and hardness increased with prolonging exposure time.