In order to control styrene composition and block molecular weight，styrene reversible addition-fragmentation chain transfer（RAFT），bulk and mini-emulsion polymerization processes were performed with 1-phenylethyl phenyldithioacetate（PEPDTA）during styrene homopolymerization and copolymerization with other monomers.For styrene bulk RAFT polymerization，retardation was not important because the cross-termination rate of propagating radical with intermediate radical was much slower than the termination rate of double propagating radicals.It was difficult to obtain high conversion and molecular weight with narrow polydispersity index（PDI）due to its slow reaction rate.For styrene mini-emulsion RAFT polymerization，the induction period and retardation were more obvious with increasing PEPDTA concentration，and the polymerization rate was much faster.Meanwhile，the number of particles decreased and its distribution became broader.The molecular weight increased linearly with increasing conversion，and its molecular weight distribution became much narrower when PEPDTA concentration increased.The theoretical modeling curves formulated were close to the experimental data，and RAFT mini-emulsion polymerization kinetics model based on the Smith-Ewart equation could well predict the experimental processes.