The invention discloses a method for storing waste concrete and sealing carbon dioxide in a newly-abandoned coal mine. All roadways of the newly-abandoned coal mine are separated, and the size of eachspace after separation is determined; from the end farthest away from a portal of the newly-abandoned coal mine, separation walls are constructed in sequence according to the determined size of eachspace after separation; a material transportation system of the newly-abandoned coal mine is adopted to transport the waste concrete into the space after separation for accumulation, and in the accumulation process, a water supply system is adopted to spray saturated lime water; sealing walls are constructed to seal the space where the waste concrete is accumulated, and high-pressure pipelines arearranged on the sealing walls; after the sealing walls meet the sealing requirements, by means of compressed air pipelines, connected with the high-pressure pipelines, of the newly-abandoned coal mine, the carbon dioxide gas is injected into the space; when injection of the carbon dioxide gas with a certain volume is completed, injection is stopped, and the high-pressure pipelines are sealed. Bymeans of the method, the purposes of waste concrete placement, newly-abandoned coal mine filling and carbon dioxide sealing can be achieved, and soil pollution and the atmospheric greenhouse effect can be reduced.