The starch of artocarpus heterophyllus lam seeds was mixed with distilled water into a solution. The biodegradable plastics were made of starch, glycerol, and chitosan on the different volume fraction of glycerol at mixing temperature 80°C. The effect of glycerol addition on the microstructures, crystal structures, mechanical strength and thermal properties of specimens are completely reported. They were prepared based on the different volume fraction of glycerol, i.e., 2, 4 dan 6 (%Vol). The crystal structures of biodegradable plastic films were investigated using x-ray diffractometer and their thermal properties were analyzed employing thermogravimetric analysis. The biodegradabilities of specimens were obtained by soil burial test method using microorganisms. The maximum mechanical strength of biodegradable plastics is obtained about 4,7 MPa.