Extrusion cooking has several advantages, such as high productivity, variety, low production cost and low pollution. The purposes of this study were using response surface methodology to investigate the effects of process variables (die diameters and numbers, rice contents) on the physical properties of extrudates. Experimental results showed that: Reducing the die numbers and diameters would increase the restriction of the dough and internal pressure before the die. Therefore, increasing the die numbers resulted an increase in extrudates bulk density; and increasing the die diameters raised the extrudates breaking force, but reduced the longitudinal and radial expansion.