The present disclosure discloses a simple preparation method of green acid-modified cyclodextrin, belonging to the field of cyclodextrin modification. Cyclodextrin and succinic acid are mutually modified by an esterification reaction in the presence of catalyst, and acid-modified cyclodextrin with different modification degrees is obtained by controlling reaction time at a high temperature or under a microwave action. The prepared modified cyclodextrin does not involve the use of toxic and harmful reagents, the modification reaction is simple, green and controllable, and the loading capacity of the modified cyclodextrin to guest molecules is remarkably improved compared with the loading capacity of the original cyclodextrin, so that the modified cyclodextrin has great application potential in the health fields such as food, medicines, and cosmetics.