In recent years, because of the particle-sieving effect of mesoporous silica, more interests have been shown in the utilization of the pores of mesoporous materials as nanoreactors so as to synthesize monodispersive nanocrystals with a uniform size. In this paper, the current research on the basic concept, synthesis method and mechanism of impregnating silica and the impregnation semiconductors inside the mesoporous channels are presented. Finally, the research trend is shown.