The utility model discloses a combined structure for a blast-furnace bottom. A carbon ramming mass is paved at the bottommost layer at the furnace bottom, and the carbon ramming mass is sequentially provided with at least one high heat conductive carbon brick layer and at least one micropore carbon brick layer from bottom to top. According to the combined structure, in light of calculation by heat transfer theory, the work condition and erosion mechanism of all parts of the blast-furnace are adequately considered, different carbon materials are selected in a targeted manner to form a blast-furnace liner structure, and the high heat conductive carbon bricks and different carbon materials are used in different work areas in the blast-furnace according to the performance indexes of the high heat conductive carbon bricks and different carbon materials, so that a stable protective 'slag iron shell' is formed in the production process of the blast-furnace, heat loss of the blast-furnace is not great, and the demand on smelting atmosphere at the bottom and the cylinder of the blast-furnace is satisfied for reasonable match. Therefore, the combined structure not only is beneficial for the blast-furnace to realize a high-yield, low-consumption and energy-saving production target, but also is beneficial for long service life of the blast-furnace, and meanwhile, construction investment of the blast-furnace is saved.