In this paper the influence regularity of the main parameters of the extrusion cooking system of barley used as beer adjunct on indexes observed was studied by experiments at the laboratory. These parameters are diameter of nozzle, barrel temperature, moisture content percentage of barley, 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, the recoverable ratio of wort extract and iodine value of wort. The research results indicate the extruded barley may be used as beer adjunct. Meanwhile the recoverable ratio of wort extract for extruded barley is higher than that for the traditional non-extruded barley.