For enhancing the conversion efficiency of the nanocrystalline photoelectrochemical cells, researchers apply themselves to the choice of the sensitization.Quantum dots have been paid much attention to by researchers due to the special and excellent properties including powerful absorption in infrared and visible region and easy preparation.In this paper, we reviewed potential application of quantum dots as sensitizer of the photoelectrochemical cell in photoelectrochemical solar energy conversion, as well as the mechanism of the sensitization.