In this work, butyl acrylate (BA) and methyl methacrylate (MMA) were used as monomers and K2S2O8 was used as the initiator to study the kinetics of two-stage soapless emulsion polymerization. The first stage of the reaction was to synthesize polyBA (PBA) seeds, and the second stage of the reaction was a seeded polymerization of MMA. The results showed that an increase of initiator concentration would increase the rate of polymerization and the number of polymer particles, but would decrease the size of the polymer particles and the weight-average molecular weight of the polymers. On the other hand, a decrease of the weight ratio of BA/MMA caused a decrease in the reaction rate and the weight-average molecular weight of the polymers in the second stage of the reaction. The morphology of emulsion particles was observed from transmission election microscopy (TEM). The polymer particles were very uniform in size and showed coreshell morphology with PBA as a core and polyMMA (PMMA) as a shell.