Now a day there is an emerging interest in replacing non-renewable additives with biodegradable compounds. Cellulose plays very important role in this modification. Their low cost and low density associated with high specific mechanical properties represent a good renewable and biodegradable alternative to the most commonly used synthetic reinforcement. The cellulose was modified by using 2-(Trifluromethyl) benzoylchloride by base catalyzed reaction. Modification of cellulose was confirmed by solubility and IR studies. The biodegradable composite films were developed by film casting method using modified cellulose with Poly (lactic acid) in different compositions. The film composite were characterized by mechanical, moisture absorption, water vapor permeability, oxygen permeability and biodegradable properties.