The utility model provides a sealing structure of a storage tank top stirring shaft in an acid-process aluminum oxide preparation process, which comprises a sealing assembly, a stirring assembly, a stirring assembly and a stirring assembly, wherein the sealing assembly is fixed on the lower surface of a storage tank top plate, covers a mounting hole in the tank top plate and forms an accommodatingspace with the tank top plate; A through hole suitable for the stirring shaft to penetrate through is formed in the sealing assembly; The air outlet pipe is positioned in the accommodating space; A connecting port and an air outlet hole are formed in the pipe wall of the containing space, the connecting port is connected with an air source, air enters the air outlet pipe from the air source and then is exhausted through the air outlet hole, and the air pressure of the containing space is increased. Through the sealing structure, the pressure intensity of the containing space can be increased,and hydrogen chloride gas is prevented from overflowing.