Gene therapy holds tremendous promise in the treatment of tumors, in which an effective delivery system plays a crucial role. Herein, a nanoscale polymeric micelle is developed to co-deliver superparamagnetic iron oxide nanoparticles (SPIONs) and siRNA targeting luciferase gene (siLuc) into tumors. In vitro studies showed that SPIO and siRNA-loaded micelles could enter cancer cells easily and they have no cytotoxicity. And in vivo studies indicated that polymeric micelle could deliver SPIO and siRNA into tumors efficiently. Our results strongly demonstrated that the novel polymeric micelle is a promising carrier for delivery of siRNA and SPIO to enable noninvasive imaging-assisted therapy in vivo.