Abstract: The influence of parameters of soybean extrusion system (diameter of die nozzle, temperature of barrel,moisture of material,speed of screw) upon soybean fat and residual oil ratio, amount of protein,soluble index of nitrogen,urease activity level of soybean extrudate and optimum parameters of extrusion system were studied in this paper. If parameters of soybean extrudate are quantified reasonably, the fat of soybean extrudate will be not basically reduced and residual oil ratio of soybean extruded meal will be less than 1%. Meanwhile solvent extraction capacity of original extractor is risen 150%. The amount of protein and amino acid of soybean extrudate will be not changed basically before or after soybean extruded. The soluble index of nitrogen and urease activity level of soybean extrudate will be decreased slightly. The procedures of crushing, steam conditioning, flaking and drying of soybeans are omitted in process of traditional and extrusion solvent extraction of oil. The milling and extruding procedures of soybeans are added merely.