The invention relates to a blow-filling method and structure for controlling the difference elevation of a mud surface after treatment and unloading of a soft foundation. The structure comprises a mud storage area which is formed by a closed cofferdam, a plurality of blow-filling openings are formed in a cofferdam dyke close to a mud collection area, the distance between every two adjacent blow-filling openings ranges from 150 m to 200 m, and water outlets are formed in the side, opposite to the blow-filling openings, of the cofferdam dyke; blow-filling pipes are installed in the blow-filling openings, the blow-filling pipes are located on the edge of the cofferdam dyke at the initial stage and gradually move deep into a blow-filling area after a beach is formed in the blow-filling area, the extension length of the blow-filling pipes each time is not larger than 50 m, and the accumulative total extension length is not smaller than 400 m; and the blow-filling radiation range of the pipe orifice of each blow-filling pipe in the blow-filling area is not smaller than 500 m. By the adoption of the technical scheme, the project period is greatly shortened, the problem that the elevation difference is large after unloading is completely solved, the problem that distribution of mud in a traditional blow-filling area is nonuniform is also solved, and the blow-filling quality is improved; and meanwhile, the blow-filling method and structure for controlling the difference elevation of the mud surface after treatment and unloading of the soft foundation further have the advantages that the structure is simple, construction is convenient, and the cost is reduced.