The copolymer of styrene-co-acrylonitrile (SAN) was synthesized by the atom transfer radical polymerization (ATRP) using FeCl3-isophthalic acid (IA)/2,2'-azobis(isobutyronitrile) catalyst system under microwave irradiation (MI). Compared with conventional heating (CH), the copolymerization rate was accelerated under MI, and the conversion of monomer rapidly achieved 30% in 38 min for MI relative to 8% for CH under other same conditions. The kinetics results indicated that RATRP of St/AN is a 'living'/controlled polymerization, corresponding to a linear increase of molecular weights with the increasing of monomer conversion and a relatively narrow polydispersities index (PDI < 1.25) when the conversion is beyond 30%. The resultant SAN was characterized by FT-IR, NMR, and GPC.