Abstract: Cellulose Nanofibrils were extracted from hybrid pennisetum (pennisetum americanum × P. purpureum) by Hot-compressed water processing, bleaching, and homogenization processing. The characterization of the fibrils by SEM and FE-TEM showed that the structure of the nanofibrils extracted from Hybrid Pennisetum was 3D network, formed by intertwining of nanofibrils, several nanometers in diameter. FTIR analysis showed that the chemical composition of the nanofibrils was mainly cellulose because hemicelluloses and lignin were significantly removed by hot-compressing treatment and bleaching. The crystallinity and thermal stability of the fibrils were examined by XRD and TGA, and the results showed that thermal stability decreased after the cellulose nanofibrils homogenized, and the crystallinity improved when the nanofibrils were hot-compressed water treated and bleached.