The development of tumor involves in m any factors, such as activating of oncogen, invalidating of cancer suppressor genes and abnorm al expressing of apoptosis genes. Because current clinical therapy can not reach the complete remission of tumor, gene therapy has already been a hopeful technique for tumor treatment. Now RNA interfere（RNAi） as studying gene and without influencing the function of normal genes, can intervene the genes that play an important role in cells canceration, and then restrain the expression of oncogene and attain the purpose of gene therapy for tumor finally. RNAi may be a new promising therapeusis.
