The invention discloses a method for preparing caffeic acid ester derivatives in the technical field of pharmaceutical chemicals. The method comprises the steps that metal trifluoromethanesulfonate is used as a Lewis acid catalyst, mixed with caffeic acid, alcohol and solvent and then subjected to an esterification reaction under a mild condition, and then a crude product is obtained; the crude product is purified, and then the caffeic acid ester derivatives are obtained. According to the method, the caffeic acid or an analogue of the caffeic acid and the alcohol are used as reaction raw materials to obtain target molecules in one step, and multiple reaction steps or operation steps are abandoned; since the metal trifluoromethanesulfonate is used as the Lewis acid catalyst for catalysis, various caffeic acid ester compounds are synthesized under general conditions, the production cycle is shortened, and a complex operation process is simplified; regarding recovery of the catalyst and the organic solvent, production cost is lowered, and emission of waste is reduced.