A series of Mg-porphyrin complex doped divinylbenzene (DVB) based porous organic polymers (POPs) were systematically afforded through the method of free radical polymerization under solvothermal conditions. These POP catalysts have physical advantages of high surface areas, hierarchical pore structures, high thermal stability and spatially separated active Mg-porphyrin sites, which lead to very high efficiency in the conversion of CO2 to cyclic carbonates with the aid of tetra-n-butyl ammonium bromide (TBAB) as a nucleophile. The effect of the doping ratio (Mg-porphyrin complex to DVB) on catalytic efficiency was studied and discussed, and the detrimental embedding effect was found. The effects of reaction temperature and pressure on catalytic activity as well as other epoxide substrates were also examined fully. More importantly, under very mild conditions (30 °C, 0.1 MPa CO2), a considerable turnover number (TON) value of 1800 was obtained. The heterogeneous POP catalyst can be easily recovered and reused 10 times without loss of activity.