An HA-protein conjugate in which an HA-aldehyde derivative, in which an aldehyde group is introduced to a hyaluronic acid or a salt thereof, is conjugated to the N-terminus of a protein, and a method for preparing the same are provided. The HA-protein conjugate includes a protein drug exhibiting an excellent bioconjugation efficiency and long-term medicinal effects, and has excellent protein drug activities since the hyaluronic acid is specifically conjugated to the N-terminus of the protein. Also, since liver-targeting properties of the hyaluronic acid can be freely controlled by changing an aldehyde substitution rate of the HA-aldehyde derivative, the HA-protein conjugate can be effectively used as a protein drug for treating liver diseases, and also be useful in enabling long-term medicinal effects of a protein drug required to bypass the liver. Accordingly, the HA-protein conjugate can be effectively used for a drug delivery system of proteins.