Abstract: A kind of ascorbic acid derivates 3-O-glyco-L-ascorbic acid, their preparation methods, intermediates and uses in cosmetics. The derivates used as vitamin C precursors have better physiological effect than 2-O-?-D-glucopyranosyl ascorbic acid (AA-2G) and are more stable. Present compounds can be used in many fields, such as in cosmetics, pharmaceuticals, foodstuffs and livestock feed, and especially as whitening agents in cosmetics. The preparation method involves protecting the 5,6-dihydroxyl of ascorbic acid, then coupling with 1-haloacylglycosyl, obtaining the intermediate 3-O-(acylglycosyl)-(5,6-O-isopropylidine)-L-ascorbic acid, removing the isopropylidine and acyl from the intermediates, thereby obtaining the target substance.