The extruding and expanding experiment was studied with the black soybean meal as material, mixing corn starch by twin-screw extruder to make reconstituted powder, The best expanded technical parameters were determined, and studied the formula, the extrusion ratio, the reconstituability, the viscosity, the color of this powder flour. The optimal formula of the powder was as follows: black soybean meal 30%, corn starch 45%, sugar 15%, maltodextrin 10%, creamer 6%.