The invention relates to the technical field of polymer functional microspheres, and discloses crosslinked monodispersed polymer functional microspheres and a preparation method thereof. The microspheres are prepared through the following steps: an acrylate monomer, an initiator, a stabilizer and an alcohol water solution are well mixed, and the mixture is divided into a component A and a component B. A crosslinking agent is added into the component A, and the mixture is uniformly mixed; after heating and stirring, the component A with the crosslinking agent is dropped into the component B; and a thermostatic reaction is carried out, such that the crosslinked monodispersed polymer functional microspheres are obtained. According to the invention, a crosslinking agent-monomer mixed liquid post-dropping semi-continuous dispersion polymerization method is adopted. The obtained microspheres have the advantages of high crosslink density, uniform particle size, and good solvent resistance. The method has the advantage of simple operation. Compared to a conventional seed swelling method, the method provided by the invention is more practical, and has a potential application prospect.