The present invention relates to a reinforcing structure of unexpired concrete building floors used for reinforcing a concrete column, a concrete beam and a concrete floor slab. The structure has: at least one external column each of the at least one external column wrapping around the concrete column; at least one framework each wrapping around the concrete beam; a plurality of brackets fixedly mounted to the lower surface of the concrete floor slab, and a base plate disposed at the bottom of the concrete column, wherein the bottom of each of the at least one external column is fixed to the base plate, the top of each of the at least one external column is fixed to a corresponding one of the at least one framework, and the corresponding framework is fixed to the plurality of brackets along a length direction of the concrete beam.