In the field of puffed food processing, the objective is to produce feed with a high degree of expansion and fluffiness, which is currently a key requirement in the market. Accordingly, in order to enhance feed production efficiency and puffiness, based on a combination of CFD software Fluent numerical simulation and Box—Behnken experimental design, this paper selected screw speed, expansion temperature and feeding speed as the primary influencing factors, and adopted response surface analysis method to optimize the pretreatment process conditions of the single‑screw extruder for processing soya bean meal materials, thereby establishing a mathematical model of the process. The findings indicated that the optimal expansion temperature was 109.96 ℃, the optimal feeding speed was 0.07 m/s, and the optimal screw speed was 117.66 r/min. Finally, by comparing the results of the expansion degree of different groups of materials, it was found that under the process conditions of expansion temperature of 110 ℃, feeding speed of 0.07 m/s, and screw speed of 120 r/min, the feed produced had the highest expansion degree of 3.85, which verified the feasibility of the above optimal scheme.