The optimal conditions of supercritical fluid extraction were obtained as follows, CO2 flow rate of 8L/h, static extraction time of 120min, dynamic extraction time of 60min, entrainer ethanol dosage of 3mL/g defatted soybean residues, extraction temperature of 55℃ and extraction pressure of 30MPa, by single factor test and four factors and three levels orthogonal design method. The kinetic model of supercritical fluid extraction accurately described the distribution of isoflavone genistin in the extraction bed was developed based on adsorption and desorption theory. The model parameter kLa was determined by BP neural network and trial and error method. 