Cellulose, one of the most abundant natural biopolymer, has attracted increasing interest due to its renewability, nontoxicity, biodegradability, stability and low cost, which has been used as an important and fundamental materials in various fields such as paper, medicines, plastics, cosmetics, etc. After years of research, the unique structure of cellulose has been revealed and it consists of highly stereo-regular linear homopolysaccharide of (3-1,4-linked anhydro-D-glucose units with a high aspect ratio (2-50 nm wide and hundreds of nanometers long), which endows the cellulose with a high tensile stiffness (2-6 GPa). The cellulose nanomaterials containing highly cellu¬lose crystalline blocks also exhibit some other excellent properties, for instance, high elastic modulus (140-150 GPa), low ther¬mal expansion coefficient in the axial direction, high specific surface areas and chemical reactivity.