Ethylene-propylene-diene monomer (EPDM) ultrafine fibers have been prepared by electrospinning method, with an average diameter of micron grade and fibrous structural morphology. The effects of experimental parameters, including the solution concentration, applied voltage, collection distance, and flow rate, were investigated carefully. It shows that the morphology and fiber diameter of electrospun EPDM fibers are greatly influenced by the process parameters. Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry apparatuses were used to analyze the structural and thermal properties of the electrospun fiber mat, with EPDM cast film as a comparison. The results reveal that the electrospun fiber mat has a lower degree of crystallinity than its cast film.