Abstract: Influence regularity of the main parameters of the extrusion system for extrusion cooking of degermed maize used as beer adjunct to observed indexes was studied through laboratory experiments. These parameters include nozzle diameter, barrel temperature, degermed maize moisture, screw speed and the distance from the internal surface of die plate to the end surface of the end of screw. The indexes include the filtration speed and recoverable ratio of wort extract and the iodine value of mash. The research results indicate that the extruded degermed maize may be used as beer adjunct, for which the starch in mash is degraded completely in saccharifying. Meanwhile the utilizable ratio of starch in mash is better.