Composite material as well as preparation method and application thereof

The invention relates to a composite material as well as a preparation method and application thereof. The composite material comprises a ceramic matrix and porous iron nanoparticles, the porous iron nanoparticles are dispersed in the ceramic matrix; the thickness of the composite material is 10-150 microns; the ceramic matrix is porous ceramic with the porosity of 10-40%; the content of the porous iron nanoparticles is 41-93%, and the content of the ceramic matrix is 7-59%; the preparation method comprises the following steps: mixing and dispersing iron oxide nanoparticles and a ceramic material in a liquid medium to obtain slurry; preparing the slurry into a thin strip material, and drying; sintering is performed; performing reduction; the composite material is used in a self-heating bag for heating baits and food in the air. The technical problem to be solved is how to provide the anhydrous self-heating composite material, so that during preparation of the anhydrous self-heating composite material, a high-