Polystyrene crosslinked microspheres were prepared by soap-free emulsion polymerization using styrene (St) and divinylbenzene (DVB) as monomers; then, the microporous structure was knitted by the Friedel-Crafts alkylation reaction, and the Au nanoparticles (AuNPs) were loaded into the pores through thermal reduction, to obtain AuNPs/ hyper-crosslinked microporous polymer composite microspheres. SEM and particle-size test results show that the microspheres show good monodispersity. The micropore analysis indicates that the specific surface area and the pore volume of the microporous polymer microspheres decrease with increasing DVB content, and when the DVB content is 0.1％, the specific surface area reaches a maximum of 1174.6 m2/g. After loading AuNPs, the specific surface area and the amount of micropores of the composite microspheres decrease obviously. The results of XRD and XPS analyses suggest that HAuCl4 is reduced to AuNPs. The composite microspheres show a good catalytic performance for the reduction catalyst of 4-nitrophenol.