The invention particularly relates to a preparation method of core-shell structure magnetic hydrogel nanoparticles with temperature responsiveness. Firstly, a binary functional grafted copolymer containing an efficient adsorption unit and a temperature-responsive unit containing cross-linking points is synthesized; then, the efficient adsorption unit in the copolymer is utilized for adsorbing copolymer molecules on the surfaces of magnetic nanoparticles; a cross-linking agent is introduced, the molecular structure of the temperature-responsive unit is locked, and a gel layer is formed. The defects that an existing method of constructing a hydrogel layer on the surfaces of magnetic nanoparticles is complex in step and poor in controllability, and the stability of the magnetic nanoparticles is influenced are overcome, and the preparation method has the advantages that the adsorption efficiency of the copolymer on the surfaces of the magnetic nanoparticles is high; the negative influence on the magnetic nanoparticles in the adsorption process is small; the magnetic nanoparticles are wrapped comprehensively; the gel layer structure is adjustable; the circulating performance of the hydrogel layer is stable.