RNA interference (RNAi) has been proved as a novel approach for gene therapy. However, RNAi mono-therapy only aims at single gene, it therefore may ultimately fail to cure cancers caused by polygene variation. To overcome the deficiency of RNAi mono-therapy, "combinatorial RNA interference" (coRNAi) was put forward as a new strategy. By co-expressing the inducers of RNAi triggering single or multiple targets directly and other RNA- or protein-based silencers, coRNAi keeps target genes silent, prevents carcinogenic progression and induces apoptosis of tumor cells. This paper mainly reviews the major strategies of coRNAi and their applications in cancer gene therapy.