Cellulose molecular chains are biosynthesized and self- assembled into microfibrils, which are composed of orderly crystalline domains and disordered amorphous domains. Cellulose keeps the supramolecular structures and the fiber morphology by hydrogen bonding within molecular area and van der Waals force between cellulose chains [6]. The amorphous domains are suscep- tible to acid attack because cellulose chains in these regions are randomly oriented and with a lower density. Nanocrystalline cel- lulose (NCC) extracted from natural fibers by acid is in the size of nano-scale, which demonstrates not only the features of nano- particles, but also unique strength and optical properties. It was reported that the rod-like cellulose particles acquired from differ- ent sources through acid hydrolysis are basically with a diameter from 5 to 20 nm, and a length from 100 nm to several microme- ters [7,8]. Recent researches showed that NCC had wide application prospects in nanocomposite field [6,9–11], while its application in pulp and paper has seldom been reported.