Abstract: Organic/inorganic nanocomposite films were prepared by the solution casting method by introducing sepiolite(SP) into Chitosan(CS)/Zein(ZN) matrix. The effects of SP addition on the mechanical properties and water-resistance were investigated. And the enhancement mechanism of SP loading in the matrix was also analyzed. The results revealed that the nanocomposite films have better miscibility, which resulted in the improved mechanical properties and water-resistance compared with the pure CS/ZN film. And it indicated that SP dispersed well in the CS matrix. The tensile strength increased with the increase of SP loading. When the content of SP loading was 2 wt%, the tensile strength reached the highest value of 21.1 MPa, which was increased about 8.4% comparing with pure CS/ZN. Meanwhile, the elongation at break of nanocomposites decreased from 15.3 to 7.5% with the SP loading increasing from 0% to 10 wt%. The water uptake value of nanocomposite decreased and then increased with the increase in SP loading. And the minimum value was obtained when the SP loading was 8 wt%. Furthermore, the light transmittance of the films decreased about 20% with the introduction of 6 wt% SP in the visible light regions of 800 nm.