Abstract: The quantitative method, Sodium Dodecyl Sulphate Polyacryamide Gel Electrophoresis (SDS-PAGE)-Colorimetry, of toxin proteins in various B.t. commercial products was presented. B.t. samples were pretreated with aqueous NaOH at high pH, and treated with Laemmli sample buffer, then electrophoresis was carried out. After stained with Coomassie Brilliant Blue (CBB) R-250, the band of 130KD-toxin proteins was cut out, and the absorbed CBB R-250 was eluted with pyridine. The absorbance of the eluted dye was measured at 605nm. This method characterized by relatively high accuracy and precision. Relative standard deviation (RSD) was nearly 5%. The fortified recoveries varied from 94.6%～99.2%. There were no significant differences between the data from SDS-PAGE-Colorimetry and SDS-PAGE-TLC-Scanner. The relationship between the percentage of 130KD-toxin protein and the potency of insect bioassay was studied.