The polystyrene (PS) seed emulsion was firstly prepared by soap-free emulsion polymerization. Styrene-styrene sulfonate copolymer microspheres (PS-NaSS@PS) with core-shell structure was then synthesized through polymerization of sodium p-styrenesulfonate in the PS seed emulsion. Followed by acidizing, surface sulfonated microspheres (PS-HSS@PS) was obtained. Ethyl N-phenylformimidate was synthesized with PS-HSS@PS as a recoverable catalyst. Its catalytic performance was compared with p-toluene sulfonic acid and commercially available strong acidic cation-exchange resin. The results showed that the sulfonic acid group content and the addition amount of PS-HSS@PS had a great influence on the catalytic performance. The catalytic activity of PS-HSS@ PS with high sulfonic acid content was excellent and the yield was up to 97%. The activity of PS-HSS@ PS was higher than that of srong acidic cation-exchange resin (89% of the yield), and comparable to p-toluene sulfonic acid (98% of the yield). Furthermore, PS-HSS@PS had excellent recyclability and the yield could reach 97% after 5 cycles.