The invention relates to a method for preparing a super-hydrophobic nano modified cellulose material, which comprises the following steps: adopting tetrabutyl titanate as a precursor, adopting a natural cellulose fiber as a substrate substance and depositing a nano-layer titanium dioxide film on the surface of the natural cellulose fiber by a sol-gel method; and then self-assembling a silane single layer containing long chain alkyl to obtain the super-hydrophobic nano modified cellulose material. The nano modified cellulose material has obvious super-hydrophobicity, durable chemical stabilityand self-cleaning capacity and wide application prospect in the production of the fiber materials for preventing water, damp, dirt, dust, and the like in a textile industry.