The article uses corn flour, plasticizer dioctyl phthalate (DOP), CO₂ resin, and other materials to produce biodegradable sheet materials as a substitute for plastic, and optimizes the processing conditions. The addition of plasticizers DOP, the mass ratio of CO₂ resin to ethylene vinyl acetate copolymer (EVA), as well as the addition of glycerol and corn flour, were studied through single factor determination, and their effects on the elongation at break and tear strength of the sheet were significant. The response surface Box-Behnken method was used to analyze the three factors that have a significant impact on biodegradable sheets. The final order of the influence factors was determined as follows: Glycerol addition>corn flour addition>plasticizer DOP addition. The optimal process parameters were 55 g corn flour addition, 2 mL plasticizer DOP addition, and 4 mL glycerol addition. Under these conditions, the tear strength of the biodegradable sheets produced was 3.456 N/mm, after 90 days of soil burial, the biodegradability performance was significant.