The present invention relates to a hyaluronic acid-nucleic acid conjugate for the development of in vivo nucleic acid delivery system, and the development of nucleic acid delivery system using the same. Specifically, a hyaluronic acid-nucleic acid complex wherein a hyaluronic acid-alkylenediamine conjugate and nucleic acid are connected by a disulfide bond; a composition for nucleic acid delivery comprising the hyaluronic acid-nucleic acid complex as an active ingredient; a method for preparing the hyaluronic acid-nucleic acid complex; and a method for in vivo delivery of nucleic acid, comprising administering the hyaluronic acid-nucleic acid complex to a subject are provided.