Nanocomposite chitosan-based films incorporated with drug-loaded methoxy poly(ethylene glycol)-b-poly(D,L-lactide-co-glycolide) diblock copolymers (MPEG-b-PDLLG) nanoparticles were prepared by forming drug-loaded nanoparticles in chitosan solution before suspension-solution film casting. Salicylic acid was used as a poorly-water soluble model drug. The nanocomposite films with DLL/G ratios of 100/0 and 85/15 mol% and chitosan/diblock copolymer/drug ratios of 80/1/1, 80/2/2 and 80/4/4 (w/w) were prepared and investigated. The sizes of drug-loaded nanoparticles into the chitosan films were approximate or less than 100 nm. Nanopores were observed in the resulted chitosan films incorporated with drug-loaded nanoparticles when the diblock copolymer ratio was increased up to 2. Number and size of the nanopores increased as increasing the diblock copolymer ratio. Only the nanocomposite films with chitosan/diblock copolymer/drug ratio of 80/1/1 (w/w) showed slower drug release than the chitosan film.