The present invention relates to a rare earth/metal compound functional monomer and a preparation method therefor and an application thereof. Raw materials of the functional monomer comprise a mother liquid, an organic monomer, an auxiliary agent, and deionized water. Copolymerization of the functional monomer of the present invention with high molecular polymer monomers can change a twisted side chain crystal structure of some existing polymer materials into an orderly arranged side chain crystal structure, thereby greatly improving the strength, toughness, and barrier properties of the original polymer materials. The new materials have a mechanical performance improvement factor of 0.3-3 and a thermal stability improvement of 20-60% compared to original materials, and are provided with memory properties. The functional monomer has a simple preparation process, low cost, and good application prospects.