The aim of this study is to develop well dispersed nanocomposite films including triacetate cellulose (CTA) as matrix and reinforced with cellulose nanofibers (CNF) by solution casting method. Cellulose was extracted from lemon peel (a local variety called Sudachi) and cellulose nanofiber was obtained by blending (kitchen blender). During nanocomposites processing, the key method included the nanofibers in aqueous solution were solvent-exchanged to methanol by series of centrifuging and re-dispersing steps. After that, different mixtures of CTA and nanofibers were prepared by stirring in combination with ball milling technique to achieve full dispersed solution. The optical, thermal, mechanical and dynamic mechanical properties of the nanocomposite films were characterized experimentally. With the increase nanofiber contents (1~7 wt%), the haze was slightly increased (0.2 to 0.6 %), but the transmittance was not be affected compared to that of pure CTA film (92.7 %). Therefore, we suggested that the optimal content of cellulose nanofiber was 3 wt%. The results also revealed that addition of CNF increased the tensile stress by 35%; the tensile strain by 65% and the yield stress by 43%.