The invention discloses a monolayer molybdenum disulfide-cobalt ferrite nanocomposite material and a preparation method and application thereof, and particularly relates to the field of novel nanocomposite materials. The monolayer molybdenum disulfide-cobalt ferrite nanocomposite material consists of molybdenum disulfide nanonanosheets and cobalt ferrite nanoparticles, wherein the surfaces of the molybdenum disulfide nanonanosheets are uniformly modified by the cobalt ferrite nanoparticles; the molybdenum disulfide nanonanosheets adopt layered stripping structures. The cobalt ferrite nanoparticles are assembled on the surfaces of the molybdenum disulfide nanonanosheets through a reaction in which amino groups and carboxyl groups form amide bonds; the preparation method has the advantages of low energy consumption, low cost and high yield; the obtained composite material can be used as a magnetic resonance imaging contrast agent and a controllable medicine carrier at the same time; under the guidance of a magnetic field, a medicine can reach and be enriched on a lesion site so as to achieve intelligent medicine release and real-time therapeutic effect assessment under the guidance of magnetic resonance imaging; through change of the relative contents of molybdenum disulfide and cobalt ferrite in the composite material, controllable adjustment of the magnetic resonance imaging effect and the medicine loading capacity can be achieved.