The invention belongs to the field of pharmaceutical preparations, and discloses a hyaluronic acid prodrug as well as a preparation method thereof and application thereof in transdermal delivery. According to the preparation method, hyaluronic acid is used for grafting drug molecules so as to overcome the barrier function of stratum corneum, and the drug molecules are transmitted to the subcutaneous tissues by means of intercellular space penetration and an opening of cutaneous appendages, so that drug molecular targeting and skin absorption efficiency are improved. As a carrier for administration, hyaluronic acid can effectively improve the percutaneous permeability of a drug, and helps the drug to be absorbed into the systemic circulation, thereby enabling an effective blood concentration of local or systemic treatment to be reached. Compared with the prior art, the hyaluronic acid prodrug enables the skin penetration amount of the drug molecules to be obviously increased so as to increase the utilization rate of the drug; furthermore, the hyaluronic acid prodrug facilitates the treatment of a doctor for a patient, can realize direct administration for certain diseases, and effectively reduces risks and side effects, thus having a broad application prospect.