Nanocrystalline cellulose (NCC) had been widely used in polymers due to its unique properties, but the surface hydroxyl limitd its application in hydrophobic polymers.In this paper,NCC was modified by 3-aminopropyltriethoxysilane (KH550) to improve its compatibility with ethylene propylene diene monomer (EPDM). Fourier Transforminfrared spectroscopy (FTIR) and XRD test results show that NCC successfully modified by KH550 and keep the original crystal structure intact.The vulcanization and mechanical properties test results of EPDM compound show that the addition of modified NCC promotes the vulcanization and when the addition amount of modified NCC is 6phr,the comprehensive mechanical property of EPDM vulcanizate is the best.