A vertical reactor for porous ceramic based immobilized enzyme adopting stepped layout comprises a columnar reaction cavity body formed in a base and a cover plate covering an upper port of the columnar reaction cavity body, wherein gas inlet holes are formed in the base; an absorption liquid inlet is formed in the top of the columnar reaction cavity body, a reaction product outlet is formed in the bottom, strong oxidative adsorption films and a porous plate are arranged in the columnar reaction cavity body from bottom to top, an organic glass rod is arranged along a central axis of the columnar reaction cavity body, the upper end of the organic glass rod is connected with the cover plate, the lower end is connected with the porous plate, more than two stages of immobilized enzyme carrier structures are arranged in the columnar reaction cavity body and located above the porous plate, a pressure sensor, a pH electrode, a gas sampling suction tube and a gas sampling return tube are arranged in the columnar reaction cavity body, and a pressure signal output hole, a pH electrode output hole, a gas suction hole and a gas return hole corresponding to the pressure sensor, the pH electrode, the gas sampling suction tube and the gas sampling return tube are formed in the cover plate respectively. According to the vertical reactor, the reaction rate of CO2 absorption is remarkably increased and the energy consumption is reduced.