Abstract: To study the effects of extrusion parameters of baccage sedge product characteristics and to make a preliminary optimization of the process.Four extraction parameters including particle size, water content, extrusion temperature and screw speed were optimized using central composite design and response surface methodology based on single factor investigations for achieving maximum the expansion rate. The interaction of the respective variables and their influence on the expansion rate were studied by using Box-Benhnken central composite design and response surface analysis theory. Results indicated that the particle size 60 mesh, water content 12.6%, extrusion temperture 150℃, screw speed 220r/min. Under these conditions, the expansion rate was 1.89%, compared to the theoretical value 1.90%, the relative error of 0.005%.The Baccage sedge after extrusion, slightly lower in fat and protein, however water absorption, bulging force were increased.