The invention belongs to the field of deep processing of agricultural and forest byproducts, and discloses a tea saponin purification method. According the tea saponin purification method, impurity removal is carried out on a tea saponin crude product solution, the pH value of the sample loading solution is adjusted to be alkaline to ionize acidic impurities therein, so that the impurities directly flow out of macroporous resin along with an eluent without occupying the adsorption vacancy of the macroporous resin, and therefore the adsorption capacity of the macroporous resin per unit volume to the tea saponin is greatly improved, the production efficiency of the tea saponin is effectively improved, and the production cost is lowered. The method has the advantages of being simple and safeto operate, free of pollution, high in production efficiency, low in cost, high in practicability, capable of meeting the requirements of a green production process and suitable for industrial production. The purity of the tea saponin obtained through the method can reach 94.5%, and therefore the application range of the tea saponin is greatly expanded.