The invention relates to a composition of plant extracts and application thereof in skin whitening and moisture preservation. The composition comprises the following active ingredients in percentage by weight: 5 to 90 percent of green tea extract, 5 to 50 percent of ginkgo leaf extract and 5 to 45 percent of centella extract, wherein the composition accounts for 0.5 to 20 percent when applied to preparing external products of skin, and the composition is uniformly mixed with medically-acceptable excipients or carriers in proportion to prepare products in forms of gel, cream, serosity, aqueous solution agents, emulsions or solids. The composition has the effects on skin whitening and moisture preservation without adding moisture preserving components; compared with products with similar application, the composition has stronger effects on skin whitening and moisture preservation and smaller dosage; the composition is safe, has no toxic or side effect, has low allergy rates and inflammation probability, penetrates into skin dermis, does not change the normal apoptosis process of cells, restrains tyrosinase, dopachrome tautomerase, DHICA oxidase and endothelin appropriately and balances the metabolism of melanin, so that the color and luster of the skin is more natural; and in addition, the generated skin whitening effect is definite, and the composition is convenient to use in cosmetics.