Natural killer (NK) cells as intrinsic immune cells kill tumor cells without the need for pre-stimulation by tumor antigens. Therefore, NK cell based immunotherapy has unique advantages and has made significant progress in tumor treatment. In this article, we review the development, classification, and mechanism of NK cells as well as the applications of NK cell based immunotherapies, including immune checkpoint inhibitors, adoptive cell therapy, and NK cell adapters in tumor immunity. Thus, we elucidate the principle, current status, and developmental trend of NK cellbased anti-tumor immunotherapies to provide ideas for their development and application in the field of tumor immunotherapy.