Abstract: The molecular structure and performance of polypyrrole is very different due to the difference of its synthesis methods. Utilizing a metal-organic framework (MOF) named copper pyromellitic (Cu-BTC) with three-dimensipnal (3D) mesoporous channels as the host material, the radical polymerization of pyrrole (Py) was conducted in the pores by iodine oxidation method to obtain the composite material polypyrrole@Cu-BTC (PPy@Cu-BTC). XRD, SEM, FTIR, TG and N₂ adsorption-desorption isotherm were used to characterize the prepared Cu-BTC, Py@Cu-BTC and PPy@Cu-BTC, showing the successful synthesis of polymerization in the pores. During the polymerization, the structure and morphology of Cu-BTC keep stable. Based on the charge transfer of host-guest complexation and π-π interaction, the PPy@Cu-BTC composite is a semiconductor material and has a conductivity of 10⁻⁴ S/cm which is at least four orders of magnitude higher than the conductivity of the template Cu-BTC and the as-prepared solid polypyrrole. N₂ adsorption measurement indicated that the as-synthesized PPy separated from PPy@Cu-BTC composite is porous, which has excellent absorption ability of CO₂ with a maximum absorption value of 16 cm³/g and twice as much as the absorption ability of the as-synthesized solid PPy.