Abstract: In order to overcome the problems of poor temperature, salt resistance and low mechanical strength of smart hydrogel in tertiary oil recovery. The smart hydrogel was prepared by aqueous solution polymerization with acrylamide (AM) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) as polymerization monomers. Based on the single factor experimental method, the optimal preparation process was firstly determined. Moreover, the functional strengthening modification was passed by two methods, namely, conventional modification and nano modification, and the deep profile control of smart hydrogel PBZD-1-C and PBZD-1-M was prepared. Firstly, the chemical structure and thermal stability of the smart hydrogel were characterized by FTIR, XRD and TG. Then, the water absorption, temperature resistance and salt resistance of the smart hydrogel were further explored, and the function strengthening mechanism was revealed combined with the macro properties and microstructure. As a result, the chemical structures of PBZD-1-C and PBZD-1-M meet the expected design, with good thermal stability, weight loss of about 20% at 350 ℃, good temperature and salt resistance, water absorption of 198 and 249 respectively, and effective resistance to 70000 mg/L Na⁺ and 10000 mg/L Ca²⁺ and Mg²⁺ mineralized water. Additionally, the results of function strengthening mechanism show that nano silica, ultra-fine calcium carbonate endows the PBZD-1-C and PBZD-1-M with excellent application performance mainly through its own ternary rigid ring structure, nucleating agent and reaction center.