In this paper, the continuous slow pelleting coagulation of polymer latex consisting of butadiene, styrene and methyl methacrylate (MBS) was investigated, using H2SO4 aqueous solution as coagulant. The effects of pH, temperature, feeding mode, agitation, polymer concentration and residence time on coagulation were discussed. It was found that spherical particles with uniform particle size and high bulk density were produced in the narrow range of pH. In order to obtain good particle morphology and high bulk density, well-distributed concentration, temperature and shear field in the coagulating system were required. The research will not only provide a basis for the design and production of MBS but also propose a new method for continuous pelleting coagulation.