The invention discloses nanoparticles immobilizing small-molecule catalyst and a preparation method and an application thereof, which belong to the technical field of synthesis of a high-molecular catalyst. The technical scheme is characterized in that according to a copolymer loaded with the small-molecule catalyst and a side chain contain a -COOH group, the -COOH group is subjected to deprotonation to form the copolymer with an electrification state, in-situ ion complexing effect is used for compositing with the imidazoles polyion liquid to form the nanoparticles immobilizing small-molecule catalyst, and a structure is shown in a specification. The invention also discloses a preparation method of the nanoparticles immobilizing small-molecule catalyst and an application of the nanoparticles immobilizing small-molecule catalyst in different solvents for catalyzing a multi-component reaction. The nanoparticles immobilizing small-molecule catalyst can obtain the target products with high yield in the catalysis of the multi-component reaction, such as ethanol, acetonitrile, and tetrahydrofuran, can realize effectively catalysis in water phase, and a system has the advantages of environmental protection and reduced production cost.