Disclosed in the present invention are a gene interference vector- and iron nanoparticle-based composition for killing cancer cells, and the use thereof. The composition comprises a gene interference vector and iron nanoparticles, wherein the gene interference vector is a CRISPR/Cas13a expression vector or microRNA expression vector controlled by a cancer cell specific promoter DMP, with the Cas13a-gRNA or microRNA expressed by the vector being able to inhibit, in a targeted manner, intracellular iron metabolism and the expression of reactive oxygen related genes, and the iron nanoparticles can be degraded after entering cells to produce iron ions and to increase the reactive oxygen level. The composition comprising the gene interference vector and the iron nanoparticles of the present invention can be used for preparing a new reagent for treating cancers.