Silver nanoparticles were deposited on the surface of an extruded film of linear low density polyethylene/cyclo olefin copolymer (LLDPE/COC) blend by an ultrasound-assisted method. A series of LLDPE/COC/silver nanocomposites, containing 0.02, 0.05, 0.08 and 0.1 mol/L of AgNO3 were prepared and characterized. The effect of ultrasound method on the silver deposition on the film surface was characterized as well as the effect of silver nanoparticles on their fungicidal characteristics. The silver action and biocide effect of the films were enhanced significantly as the silver content increased from 0.02 to 0.08 mol/L of AgNO3 and after that no significant enhancement was observed. From the UV-Vis analysis and transmission electron microscopic observations, the particle shape, size and size distribution were determined. Films of LLDPE/COC blends with silver deposition exhibited a noticeable increase in water vapor barrier properties with the increase in the concentration of AgNO3 and demonstrated good fungicidal activity, specifically against fungus Aspergillius niger. The observed results could be applied in the design of industrial films for packaging.