Abstract:RNA interference (RNAi) is an evolutionarily conserved post-transcriptional gene silencing mechanism mediated by small interfering RNA (siRNA) in eukaryotes， which has become a powerful tool to silence gene and holds great promising for combating human diseases. This review summarizes the current knowledge about the mechanism of RNAi， off-target effects and designing of siRNA-expressing vectors. We also compare the RNAi with CRISPR technology and further discuss the prospect of its future applications.