The invention provides a preparation method for high-purity 2-O-(beta-D-glucopyranosyl)ascorbic acid. The method comprises the following steps: (1) extraction; (2) sieving with a 100-mesh screen and centrifugal filtration; (3) concentration; (4) acidification of a concentrate; (5) passing through cationic resin; (6) passing through weak anionic resin; (7) alkalization; (8) adsorption of HCO3<-> onto highly basic anion resin; (9) strong anion resin exchange; (10) removal of sodium ions; (11) passing through the weak anionic resin; (12) concentration; (13) gel column chromatography; (14) re-concentration; (15) repeated gel column chromatography of a concentrate obtained in the step (14) and passing through a Sephadex gel column; (16) concentration and drying, etc. Thus, high-purity 2-O-(beta-D-glucopyranosyl)ascorbic acid is obtained. 2-O-(beta-D-glucopyranosyl)ascorbic acid prepared by using the method has a purity of 95 to 98% according to HPLC identification results. The method is applicable to industrial production and has great application value.