A series of polar resins based on polystyrene with carbonyl groups were synthesized and their polarity and skeleton structure were characterized. The relationship of polarity with the physical structure of the resins was investigated

and the adsorption capacity and the adsorptive selectivity properties of these resins toward stevioside and rebaudioside A were discussed in great detail. The results showed that polar resin with carbonyl group content at about 0.9～1.0 mmol/g

average pore radius at around 4.0 nm and specific surface area above 500m2/g exhibited the highest adsorptive selectivity toward stevioside.A new method for separating rebaudioside A from other stevia glycosides is also developed.