In order to improve the mechanical properties of starch-based bio-degradable plastic, mechanical properties and bio-degradability of the compound sheet made of Starch Sodium Alkenyl Succinate(SSAS) and CO2 resin were investigated. Based on the result of the sheet experiment, the best ratio of raw materials for the production of starch-based plastic using SSAS as the major starting material is as follows: SSAS 50%, CO2 resin 45%, Dioctyl Phthalate(DOP) 2%, stearic acid 1%, glycerine 1%, and talcum powder 1%. The test of performance shows that the compound sheet has good mechanical and bio-degradable properties.