Low-density, porous, millimeter-size poly (divinylbenzene) (PDVB) shells were produced by the use of a microfluidic device under ultraviolet (UV) irradiation at ambient temperature. We studied the effects of monomer concentrations and illumination times on the density, shrinkage, surface area, porosity characteristics, and compression properties of PDVB shells. It was found that actual densities, shrinkages, and surface areas of PDVB shells varied from 70 to 210 mg/cm(3), 8.5 to 15.2 %, and 457 to 848 m(2)/g, respectively, with the changes of monomer concentrations and illumination times. The analytic results of nitrogen adsorption/desorption isotherms indicated that the mesoporous structures of PDVB shells were affected by monomer concentrations and illumination times. Moreover, the photopolymerization of DVB monomers was essentially a solvent polymerization. The phase separation process induced the formation of pore structures. Different morphologies of the inwall and outwall of PDVB shells were obtained. Furthermore, a reasonable growth mechanism of PDVB shells was proposed.