An assembly-disassembly capillary-based microfluidic system was demonstrated for fabricating highly monodisperse (CV = 3.78%) poly(styrene-co-divinylbenzene-co-TPGDA) porous microspheres. The size of as-prepared ploy(SDB-TPGDA) microspheres can be precisely controlled in the size range of 250～1550 μm by manipulating flow rates radio of continuous phase to dispersed phase and continuous phase viscosity. Polymer microspheres with good sphericity （Max.D./Min.D. ＜ 1.05）were fast prepared by photopolymerization. The rate of photopolymerization increased rapidly with the increases of the TPGDA content of the mixed monomer. This study provided an effective approach to the synthesis of monodisperse polystyrene-base porous microspheres with large particle size.