The work aims to obtain chitosan films for food packaging with excellent mechanical and barrier properties. Nanocrystalline cellulose (NCC) was prepared with corncob acid hydrolysis residue cellulose by ultrasonication. The nanocrystalline cellulose/chitosan composite films (NCC-CS) made of NCC and chitosan (CS) were prepared by solution casting. The tensile strength of NCC-CS composite films with 5% (w/w) NCC content was improved by 30% compared to the pure CS films, and the water vapor permeability of NCC-CS composite films was decreased by 24%. SEM of NCC-CS composite films obtained under the optimal formulation analysis results proved that the microstructure was dense. FT-IR and XRD analysis results proved that the interaction between NCC and CS was strong. In conclusion, NCC plays an important role in improving the mechanical and barrier properties of CS films.