The work aims to prepare and characterize nanocellulose from cassava residue, so as to increase the way of making good use of cassava residue for its high-value utilization. Nanocellulose was prepared from cassava residue by high pressure homogenization after enzyme treatment and bleaching. The cassava residue was characterized and analyzed by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, infrared spectroscopy, X-ray diffractometry and thermal stability analysis. After enzymatic hydrolysis and bleaching, the cellulose content increased from 20.21% to 77.39%, the starch content decreased from 50.39% to 1.87%, the hemicellulose content decreased from 18.38% to 5.11%, and the lignin content decreased from 3.69% to 0.74%. The cassava residue fibers are homogenized at 103.425 MPa for 30 times and successfully prepare nanocellulose. The results of transmission electron microscopy and atomic force microscopy indicate that, the diameter of CNF is about 10 nm. However, amylase treatment, bleaching and high pressure homogenization do not change the crystal structure of cassava residue fiber, and it is still cellulose I.