Abstract: Taking the condition of adding 0.5% activated clay, with the decolorization rate as index, the effect of combing VIS-450 light with activated clay on decoloring the soybean oil was studied. The single factor test and response surface method was used to optimal the conditions of decolorization. The optimal conditions were as follows:current intensity of 21.3A, temperature of 78.8℃, time of 18.7min, stirring speed of 80r/min. The rate of decolorization rate was 97. 8% under the optimal conditions. In addition, the oil color was stable after decolorization, and could be place a long time, difficult to return to the color.