Abstract: Molecularly imprinting polymer microspheres for 4-aminopyridine were prepared by means of an emulsifier-free seed emulsion polymerization from ethyl acrylate and styrene using octanol and a very small amount of OS as the dispersive reagent. When the octanol and OS were employed at certain ratios,a small size and uniform distribution of the microspheres were observed. The optimal condition was found, i. e.，the dosage of octanol was 3 . 0 wt，weight ratio of ethyl acrylate/styrene was 1:0 .229，PH was 8 .0，and the polymerization temperature was 85 ℃

Key words: molecularly imprinted polymeric microsphere, synthesis, particle bulk, size distribution, emulsifier-free emulsion polymerization