Abstract: Macroporous polymers were prepared with post-crosslinking of low crosslin-ked polystyrene and cyanuric chloride through Friedel-Crafts reactions. The authors studied thoroughly the effects of reaction conditions such as reaction temperature, reaction time, and reagent ratios on the pore structures of polymers. The surface area and pore volume of the resin prepared are high as 500m³/g and 0.3-0.5ml/g respectively, and the skeletal densities of the resins are even higher than 1.3g/ml. The resins have almost the same swelling coefficient in various solvents.