Bioplastic from LDPE and durian seed starch has lack physicochemical properties compared with bioplastic from LDPE and sago starch. Addition of chitosan-gelatin in bioplastic has potential to improve physicochemical properties and biodegradation degree of bioplastic. This research was aim to investigate the effect from addition of chitosan-gelatin to physicochemical properties and biodegradation degree of bioplastic. Bioplastic LDPE were made with variation of durian seed starch concentration (10%, 30%, 50%) and ratio between starch and chitosan-gelatin (1:1) concentration (100:0, 75:25, 50:50). Bioplastic were buried in soil for 5 weeks. The weight measurement and mechanical properties of bioplastic, soil’s pH value, and evolution of CO2 were observed every week. Bioplastic with 10% concentration of durian seed starch show the highest value of tensile strength, with result 0.102±0.003 MPa and bioplastic with 10% concentration of durian seed starch and 0% of chitosan-gelatin show the highest value of elongation at break 23.657±8.03%. The highest value of Modulus Young was showed from bioplastic with 50% concentration of durian seed starch, with result 8.443±1.13 N/mm2. The highest biodegradation degree is bioplastic with 50% concentration of durian seed starch and 50% of chitosan-gelatin, with percentage of loss weight 35.453±11.80%. The addition of chitosan-gelatin does not impact on tensile strength and Modulus Young of bioplastic, but can decrease elongation at break and improve biodegradation degree of bioplastic.