This research deals with study of Degradation behavior of starch blended with different percentage of polypropylene (PP) .Twin screw extruder at 160- 190 °C and 50 rpm is used for manufacture of blend sheet. Degradation test achieved according to ASTM standard (D 638 IV and D570-98). Studies on their degradation properties were carried out by Soil burial test, Water absorption test and Hydrolysis test. The morphology test of the polypropylene / starch blend samples was obviously seen in the (Dino- Light- Digital Microscope), Results of soil burial test show that tensile strength and percentage of elongation of polypropylene / starch blend decrease with increasing the starch content and burial time. The hydrolysis test show the weight losses increasing with the increasing amount of starch. High percent of polypropylene found to decrease the amount of water absorption of the blend. The physical appearance and morphology studies of polypropylene / starch blend after burial test in soil and hydrolysis in water environment showed that all blend samples was obviously changed after 90-day study period, whereas the pure polypropylene samples remained unchanged.