Abstract: Batch cationic emulsion polymerization was carried out with styrene(St) and butyl acrylate (BA) as non-ionic monomer, cetyl trimethyl ammonium chloride(CTAC) as emulsifier, and Azobis isobutyl amidine hydrochloride(AIBA) or Azo diisopropyl imidazoline hydrochloride(AIBI) as initiator. The effects of amounts and molecule structures of initiators on instantaneous conversion, latex particle size, PDI and particle morphology were analyzed. Results showed that higher initiator amount resulted in higher instantaneous conversion rate, smaller particle size and higher PDI. Besides, higher instantaneous conversion rate and smaller particle size were obtained when AIBI was used as initiator.