Abstract: The chicken sternal cartilage was used as the raw material and the chondroitin sulfate extraction yield as the target to withdraw the method by ultrasonic assisted alkali-enzymatic. Firstly, the ranges of all affecting factors were determined by single factor experiment and Box-Behnken center combination experimental design used to set up two times multiterm mathematical model. The result indicated that the data results significantly and the optimum conditions of ultrasonic assisted alkali-enzymatic were obtained as follows :the alkali concentration was 4%, enzyme dosage was 1.4g/L, ratio material to solvent was 1000 ∶5923 (g/mL) , and the chondroitin sulfate extraction yield was 23.94%. Determined the extraction of substances through the UV spectrum detection of chondroitin sulfate.