This research aimed to determine the optimal sand mold mixture’s ratio by using return sand bentonite water content and new sand component. Then the properties of the mixture according to the standards of American Foundrymen’s Society include the ability of compactability moisture content permeability and green compressive strength. This study applied mixture experiments and response surface methodology to determine an optimal sand mold mixture components condition. After the experiment and linear programming it indicated that the condition was at return sand (95.5387 %) bentonite (1.130102 %) water content (2.331196 %) and new sand (1 %). The green sand mold has compactability (58.37923 %) permeability (73.80148 %) moisture 6.5 % and green compressive strength (0.53 Kg/cm2). At this condition the cost is 11.31579 baths per kilogram.