NOVELTY - Extracting and purifying tea saponin involves adding de-oiled tea seed after degreasing to water, extracting and separating to obtain aqueous extract and tea seed meal; adding meal to water and extracting again, separating, combining and separating to obtain aqueous extract; adding chitosan solution whose volume is 1/5-1/10 of aqueous extract and having mass concentration of 1-5% to extract, performing reaction, separating to obtain sediment comprising saponin at lower layer; adding ethanol; stirring and extracting; removing impurities; and performing vacuum condensation and spray drying.    USE - For extracting and purifying high-purity tea saponin (claimed) used as food additive.    ADVANTAGE - The method improves the purity of the tea saponin, reduces the pollution and expands the application range of the product of tea saponin. The method provides a simple, low energy consuming and safe method for extracting tea saponin that can be used for many industries and fields.    DETAILED DESCRIPTION - Extracting and purifying high-purity tea saponin involves adding de-oiled tea seed after degreasing to water, extracting for 2-5 hours at 50-80 degrees C, and then separating to obtain the aqueous extract and tea seed meal; adding the tea seed meal to water and extracting it again for 2-5 hours at 50-80 degrees C again, then separating, combining and separating to obtain the aqueous extract; adding chitosan solution whose volume is 1/5-1/10 of the aqueous extract and having mass concentration of 1-5% to the aqueous extract, performing reaction at 40-60 degrees C for 30-60 minutes, then separating to obtain the sediment comprising tea saponin at the lower layer; adding ethanol solution at a volume concentration of 70-90% to the sediment comprising tea saponin; stirring the mixture and extracting the mixture for 2-5 hours at 60-70 degrees C; removing solid impurities to obtain the ethanol solution comprising tea saponin; distilling the ethanol solution comprising tea saponin; and performing vacuum condensation and spray drying for the rest solution, to obtain tea saponin powder.