The invention particularly discloses an intelligent targeting and environmental dual-responsibility siRNA [short interfering RNA (ribonucleic acid)] delivery system for tumor, a preparation method and application. The siRNA delivery system is characterized in that siRNA is concentrated and compounded in nanometer particle nucleuses by the aid of acid-sensitive amphiphilic three-block polymers, and intermolecular disulfide bonds are formed by PAsp(MEA) on sub-surfaces, so that the siRNA can be protected, and the intelligent targeting and environmental dual-responsibility siRNA delivery system can respond to release of the siRNA in reductive cytoplasm. The acid-sensitive amphiphilic three-block polymers comprise polyethylene glycol block-intermediate block-acid-sensitive block three-block copolymers, intermediate blocks comprise polyaspartate acyl mercaptoethylamine, and acid-sensitive blocks comprise poly (diisopropyl amine) ethyl methacrylate. The intelligent targeting and environmental dual-responsibility siRNA delivery system, the preparation method and the application have the advantages that the siRNA delivery system can be applied to preparing intelligent targeting siRNA nanometer medicines for the tumor and is low in N/P ratio dependence degree, and the siRNA can be quickly and completely released at targets; a novel idea can be provided for gene delivery systems, and the intelligent targeting and environmental dual-responsibility siRNA delivery system, the preparation method and the application have important significance on preparing clinical diagnosis and treatment medicines for the tumor.