Durian seed is a waste but it has a lot of starch content, and the utilization of durian seed still limited. Bioplastic made from durian seed starch was less good than bioplastic made from sago starch in color and physical properties. This research was aimed to study the characteristic of bioplastic from mixed LDPE and sago-durian seed starch blend. The concentration of starch (10, 30, 50%) in each ratio of sago starch to durian seed starch (0:100; 30:70; 70:30; 100:0) toward the physical characteristic and biodegradation of bioplastic was observed in this study. Prior to soil burial, physical characteristics including color (whiteness) and mechanical properties were observed. The highest whiteness value was obtained from bioplastic contain 10% of starch with ratio 100:0. The higher the concentration of starch decreased the mechanical properties of bioplastic, whereas the ratio of starch had no effect towards any mechanical properties. Soil burial was conducted for 5 weeks, then the biodegradability and mechanical properties was observed afterwards. The mechanical properties showed a lower value after soil burial. The higher the addition of starch was proven to increase the biodegradability of bioplastic.