Provided are an siRNA-polymer conjugate, and a method for preparing the same, and more specifically, to a hybrid conjugate formed by covalently bonding siRNA and a polymeric compound for improving the in vivo stability of siRNA, and to a preparation method of the hybrid conjugate. The conjugate of the present invention can improve the in vivo stability of siRNA, thereby achieving an efficient delivery of therapeutic siRNA into cells and exhibiting the activity of siRNA even with a small dose of a relative low concentration. Therefore, the conjugate can advantageously be used as not only an siRNA treatment tool for cancers and other infectious disease, but also a novel type siRNA delivery system.