Abstract: Abstract:【OBJECTIVE】In order to get the pure exopolysaccharides produced by Streptococcus thermophilus Tx from Tibetan Kefir. The purification methods were analyzed, and at last the best purification method was found;【METHOD】Sepharose CL-6B was used to make a classical purification, Using ultraviolet scan and chromatogram to identify the purification effect, the purification detection;【RESULTS】Optimization purification conditions: adoption sodium chloride 0.05～0.06 mol/L, the velocity 0.25 mL/min, the sample concentration 1.0 mg/mL, the sample capacity 1.0 mL;【CONCLUSION】On optimization purification conditions EPS purity is 98.01%, 1.4 times larger than former, which provides the basement for the study of EPS structure and function.