RNA interfering(RNAi) is represents an evolutionarily conserved cellular defense mechanism to control the expression of foreign genes in most eukaryotes.With the definitude of its mechanism and the improvement of the experimental technology problems,it has been universally used in many fields of tumor researches.This paper reviewed applied advancement of tumor researches in the fields of studying multi-drug resistance,preventing invasion and metastasis of tumor,regulating cell apoptosis,cell signal conducti...