Disclosed is a tumor-targeting fusion protein comprising at least (i) a IL-15 peptide or a variant or functional fragment thereof, (ii) a IL-15Rα polypeptide or a variant or functional fragment thereof, (iii) a Fc domain or a variant or functional fragment thereof, and (iv) a RGD polypeptide or a variant thereof. The fusion protein is preferably configured as RGD polypeptide-Fc domain-IL-15 polypeptide-IL-15Rα polypeptide. The tumor-targeting fusion proteins provided herein improves the anti-tumor effects of IL-15 and prolongs the half-life of IL-15, while targeting tumor sites and acting upon tumor cells. In addition, the fusion proteins are capable of being expressed at high efficiency and purified. The high efficiency of anti-tumor activity enables the fusion proteins to be an excellent candidate for tumor immunotherapy.