The invention discloses a flue gas decarburization system and method utilizing a magnetized gas-liquid-solid three phase bed, and belongs to the technical field of atmospheric pollutant treatment. The system comprises a magnetized three phase bed absorbing tower, a rich and lean solution heat exchanger, a regeneration tower, and a CO2 storage device. The magnetized three phase bed absorbing tower is connected to the rich and lean solution heat exchanger, the regeneration tower and the CO2 storage device in sequence through pipelines. The regeneration tower is provided with a lean solution outlet, is connected to the rich and lean solution heat exchanger through a pipeline, and is connected to the magnetized three phase bed absorbing tower through a pipeline. CO2 is absorbed by an absorbing agent under the co-effect of magnetic field and magnetic particles. A CO2 rich solution flows through the rich and lean solution heat exchanger and releases CO2 in the regeneration tower, and a CO2 lean solution is obtained at the same time. The lean solution flows through the rich and lean solution heat exchanger, goes back to the three phase bed, and keeps on absorbing CO2. The system utilizes a magnetic field and magnetic particles to increase the CO2 absorption efficiency of an absorbing agent; the rich solution and lean solution both carry with few magnetic particles, which can enhance the heat exchange between rich and lean solutions and the regeneration of absorbing solution and the energy consumption of regeneration is reduced therefore.