Aim:In vivo stability and consequent high tumor accumulation is highly desired for nonviral gene therapy. Materials & methods: Here, a well-defined cationic nanogel system (NPS) was facilely prepared for gastric tumor therapy. Results: The physical chemical properties of NPS were finely regulated and investigated. In vitro transfer efficiency of NPS was obviously promoted due to stable polyplex structure, small size, narrow size distribution and weak surface potential. Interestingly, the transfection was further enhanced by its passive targeting function. Intratumor accumulation was significantly promoted post intravenous administrated to Balb/c nude mice. Thus, the established gastric tumor (N87) growth was significantly inhibited by p53 as delivered by NPS. Conclusion: Such noncytotoxic cationic thermosensitive NPS can be effective for practicable gene therapy.