Cellulose-based composites packaging films containing various amounts of modified nano-SiO2 were prepared by utilizing hardwood pulps as natural cellulose resource through NMMO-technology to improve the mechanical properties, permeability for oxygen and water vapor etc. The tensile strength, elongation at break, thermal stability and permeability of the cellulose composites films as a function of the content of modified nano-SiO2 were studied. The investigation suggested that the capabilities of composites films with 2 wt.% modified nano-SiO2 added were improved largely, compared to pure cellulose films, when the diameter of particles is 30nm. The tensile strength was increased from 8.95 to 17.37 MPa and the elongation at break of the cellulose composites films was improved from 41.11% to 58.34%. The composites films with rational mechanical properties have adjustable oxygen permeability (7.90×10-15-72.18×10-15 cm3·cm/cm2·s·Pa) and water vapor permeability (7.12×10-13-5.32×10-13g·cm/cm2·s·Pa). And thermal stability of the composites films was advanced through adding modified nano-SiO2.