An apparatus for collecting carbon dioxide from flue gas of a power plant. The apparatus includes an absorption tower, a sedimentation pool including slanting boards, a regeneration tower, a gas-liquid separator, a desiccator, a compressor, and a condenser. A rich solution is adapted to flow from a bottom of the absorption tower into the sedimentation pool for stratification. A gas outlet of the gas-liquid separator is in series connection with the desiccator, the compressor, the condenser, and a liquid carbon dioxide storage tank.