Natural killer (NK) cells are important immune cells in the human body and are also the main lymphocytes in the liver. They are considered the first defense mechanism against tumor and have a significant impact on the development and progression of liver cancer. The characteristics of NK cells help them become a new choice for immunotherapy, and NK cell-based immunotherapy may succeed in the treatment of liver cancer. This article reviews the biological characteristics of NK cells, their role in the development and progression of liver cancer, and the research advances in related treatment.