Using styrene as raw material, potassium persulfate as an initiator and β-cyclodextrin as a stabilizer, polystyrene microspheres were successfully prepared by means of soap-free emulsion polymerization method. The microstructures were characterized with SEM, and the effects of the stabilizer dosage, the styrene monomer dosage and initiator dosage on the particle size distribution were studied. The results show that polystyrene microspheres with different particle sizes and good monodispersity were obtained by changing amount of stabilizer and the styrene monomer dosage and dosage of initiator appropriately.