Cross-linked polystyrene microcapsules with numerous uniform spherical pores were prepared by in situ polymerization of styrene-divinylbenzene in a (W/O/W) emulsion system. At first, the (W/O) emulsion was prepared by dispersing an aqueous inorganic salt solution into the organic solution consisting of styrene monomer, divinyl-benzene, ADVN, hexaglicerine ricynoreic acid and toluene. Then, (W/O/W) emulsion was prepared by dispersing the (W/O) emulsion into the outer aqueous solution containing sodium dodecylbenzene-sulfonic acid and polyvinylalcohol. Microcapsules having porous spaces in the sphere and on the surface were formed by in situ polymerization. The characteristics of microcapsules were found to be controlled by the operating conditions as salt in inner aqueous solution, the ratio of styrene and ADVN, concentration of styrene and surfactant in oil phase and fraction of inner aqueous solution.