Abstract: The research aimed to apply of fluidized bed air superfine grinding of bean dregs. On the basis of single factor experiments,the best process parameters were determined by the response surface methodology. The ground powder and micronized powder before and after pulverized were compared and analyzed through the particle size distribution,color,microstructure and infrared spectrum. The results showed that the optimum grinding process were as follows:feed quantity 93 g,grinding frequency 32 Hz,grinding pressure 0.8 MPa. Under these conditions,the median particle size(D₅₀)of soybean residue powder was 14.98 μm,the color of the micronized powder was bright and white,the particle distribution was uniform,the specific surface area increased and the structure change of the powder was very little.