Conventional oilfield plugging agent in the deep water plugging of oil wells is prone to degradation and failure，the plugging agent is very easy to be damaged to lose the plugging effect after the absorption of liquid，it is difficult to meet the needs of deep water plugging. Based on the physical crosslinking network of CMC@Fe₃O₄，the physicochemical dual network self-healing hydrogel P（AM/AMPS/NVP）/CMC@Fe₃O₄ was constructed by using acrylamide（AM），2-acrylamido-2-methylpropanesulfonic acid（AMPS） and N-vinylpyrrolidone（NVP） as copolymerization monomers，potassium persulphate （KSP） as the initiator， hydroquinone（HQ）and hexamethylenetetramine（HMTA）as the crosslinking agent. The performance of gel strength，self-healing performance and temperature and salt resistance of the gel system were characterized. The optimum formulation of the self-healing gel system was as follows，91.6% CMC@Fe₃O₄ dispersion，5.6% AM，2.4% AMPS，0.4% NVP，pH= 9，the initiator KSP dosage was 0.8% by mass of the monomer，and the cross-linkers were 0.6% HQ and 0.6% HMTA. The gel strength of the gel was 230.6 Pa. The dehydration rate was only 6.21% after aging for 30 d at a high temperature of 130 ℃ and a high salinity of 2.2×10⁵ mg/L， exhibiting good temperature and salt resistance. The plugging rate of the gel system to the sand-filled pipe with water phase permeability of about 388 μm² was above 99%，and the breakthrough pressure was above 2.12 MPa，which could meet the needs of oilfield plugging. The self-healing of the gel could be achieved after aged at the temperature of 130 ℃ for 1 h，with a gel fracture elongation of 275% and a repair efficiency of 100%. the dual-network self-healing hydrogel demonstrates excellent performance in terms of gel strength，resistance to temperature and salt，sealing effectiveness and self-healing properties，and meets the requirements for deep plugging in oilfields.