thermoplastic starch (TPS) was prepared from starch, sorbitol and PCL by twin extruder and then blends were prepared from linear low density polyethylene (LLDPE) and TPS. Mechanical properties, thermal properties, and morphology were investigated and also biodegradability was studied by using aerobic composting method (ISO 14855). Tensile strength, modulus and elongation at break decreased as the content of TPS increased. The melting temperatures of blends were not changed. so this showed that LLDPE and TPS were immiscible. The morphology of the fractured surface of blend film was investigated by scanning electron microscopy (SEM). After 45 days composting, the biodegradability of blends increased as the content of TPS increased.