Abstract: In order to further study the efficient demulsification mechanism of chemical flooding, a new type of magnetic nanoparticle Fe₃O₄@CPAM with different monomer ratios (mass fraction of acrylamide and methacryloyloxyethyl trimethyl ammonium chloride) was synthesized, and this successful synthesis was confirmed through a series of characterization methods such as X-ray diffraction analysis, Fourier transform infrared spectroscopy analysis, thermogravimetric analysis, and vibrating sample magnetometer analysis. A comparative analysis was conducted on the effects of Fe₃O₄, Fe₃O₄@CPAM (monomer 20%), and Fe₃O₄@CPAM (monomer 25%) concentrations on the microwave demulsification of heavy oil. The study shows that a too high concentration can inhibit the demulsification effect, and only when the concentration is appropriate, can microwave coordinate with magnetic nanoparticles for demulsification. In addition, the promotion mechanism of magnetic nanoparticles for microwave demulsification was also revealed from the perspectives of oil droplet distribution and Zeta potential. The results show that when the magnetic nanoparticles Fe₃O₄@CPAM (monomer 20%) are used alone, the diversion ratio of the emulsion can reach 95.24% at the mass concentration of 175 mg/L and sedimentation time of 30 minutes; when the magnetic nanoparticles Fe₃O₄@CPAM (monomer 25%) are only used, the diversion ratio of the emulsion can reach 100% at the mass concentration of 200 mg/L and sedimentation time of 10 minutes. At the microwave radiation power of 200 W and radiation time of 20 s, the mass concentrations of magnetic nanoparticles Fe₃O₄@CPAM (monomer 20%) and Fe₃O₄@CPAM (monomer 25%) are 75 mg/L and 50 mg/L, and the sedimentation durations are 30 minutes and 20 minutes, respectively; the diversion ratio of the emulsion can reach 96.49% and 99.10%, respectively. The above results have confirmed that there is a coupling synergy between microwave and the new-type magnetic nanoparticles, which can significantly reduce the amount of magnetic nanoparticles used.