Taking bean dregs as the main raw material, compounding miscellaneous grains and homology of medicine and food to prepare soybean-based multigrain rice paste. The material addition amount, screw speed, and the temperature of the zone III barrel were used as response factors, and the gelatinization degree was the investigation index. On the basis of the single factor experiment, the optimal process conditions for the preparation of bean-based multigrain rice paste by the extrusion-expansion technique were obtained by Design-Expert 8.0.6 design test. The results showed that when the material addition amount was 12.5%, the screw rotation speed was 330 r/min, and the III zone barrel temperature was 160 ℃, the maximum expansion degree was 91.47%. The bean-based multigrain rice prepared under the optimal conditions had a high degree of gelatinization, with fine taste and rich flavor, meanwhile it was not easy to agglomerate.