The immune system in responding to HIV/SIV infection shows complicated and not understandable. Recently, the immune mechanism of NK cells, which plays a significant role in common antiviral reaction as the major component of innate system, becomes hot issue in the field of HIV/SIV infection research. Many studies have demonstrated that the distribution of NK cell subsets and the function are abnormal and disordered during the chronic phase of HIV/SIV infection, which has meaningful association with the high level of virus application. In addition, the changes of chemokine receptors expressed on NK cells surface result in the re-distribution of NK cells in different lymphoid tissues. However, it has shown that the expression of the functional receptor KIR3DL1 and KIR3DS on NK cells are useful for the protection of HIV infection and the disease progress. In this review, the effect of NK cells and immune mechanism of NK cells in HIV/SIV infection are summarized.