One of the observable trends in the field of plastics in recent years is the possible shift from fossil fuel based resources to that of renewable origins. Some of the factors causing this shift include: rising oil prices and increased amount of materials being landfilled. So, the development of new greener composite materials is very important purpose in the industry. The application of edible polymer (e.q., starch) in plastics is also inappropriate since starch is a worldwide food source. For these reasons, we focused on the use of inexpensive and nonfood natural polymer, such as lignin, in polymer applications. Lignins are the second most abundant biopolymeric materials in the world, and are well-known biodegradable, functional and natural polymers with a unique biosynthesis pathway in lignocellulosic plants. Combinations of lignin with other synthetic thermoplastic polymers have been widely investigated. Among the various thermoplastics, LLDPE is important thermoplastics due to their having a good combination of properties, such as processability, flexibility and a glossy surface. The composite of hydrophobic matrix polymer such as LLDPE with hydrophilic lignin and the lignin fragment would not be compatibles hence these composites need reinforcing fillers are used after chemical modifications. The functional groups of the lignin can be chemically modified by well-known methods such as esterification, etherification and copolymerization. From among the processes, acetylation, which results the substitution of hydroxyl group to acetyl group, is believe to be one of the highly promising process for thermoplastic. Afterward, characteristics of the acetylated lignin/LLDPE composite films, such as morphological, thermal, rheological, and mechanical properties were investigated. The acetylated lignin/LLDPE composite film is expect to give such advantages compare to conventional pristine LLDPE films including, cost down, higher modulus while maintain the processability.