The invention relates to the technical field of converter smelting, in particular to a top and bottom combined blown converter. The top and bottom combined blown converter comprises a bottom blown device which is arranged on the bottom of a converter body; a cowling cover is arranged at the furnace mouth of the converter body; one end of a dust-removing flue penetrates through a flue through hole to extend in the furnace body of the converter body, and the other end of the dust-removing flue is connected with a dust-removing fan; an air seal device comprises a gas generating device, a gas inflating cavity and a gas flow pipeline, the air inflating cavity is arranged at the furnace mouth between a cowling and the converter body, and the air inflating cavity communicates with the air generating device through the air flow pipeline; the air inflating cavity is annular and provided with air holes; the gas produced by the air generating device flows through the air flow pipeline into the air inflating cavity and is exhausted through the air holes so as to neutralize the difference value between the extraction flow of the dust-removing fan and the gas flow in the converter body. The top and bottom combined blown converter can solve the problem of negative pressure existing at the furnace mouth of the converter, and prevent the air from entering the converter from the furnace mouth, and the carbon and oxygen equilibrium content in the liquid steel at the end-point of the converter smelting is reduced.