SiRNA comes from double-stranded RNA,which is processed into a small molecular fragment by Dicer.21-25nt siRNA,as the key effector molecules to the RNAi process,can inhibit gene expression with high specificity and high efficiency in mammalian cells.Currently,RNAi has been widely applied in a variety of cancer.RNAi has many active research explorations of the tumor development,metastasis and treatment in gastrointestinal cancer.