Abstract: Nanocomposite films were prepared from a suspension of cellulose nanocrystals as filler and polyvinyl alcohol as polymeric matrix. After the suspensions of cellulose nanocrystals and polyvinyl alcohol were mixed homogeneously, nanocomposite films were obtained by casting and evaporating. The morphology and structure of cellulose nanocrystals and the properties of nanocomposite films affected by cellulose content were characterized and analyzed. The rod-liked cellulose nanocrystals were about 20 nm in diameter and 200 nm in length. The nanocomposite films were uniform and stable, and showed an increase in thermal stability and tensile strength with an increase of the fillers content.