The invention provides a novel dust removal device and method for a process for extracting aluminum oxide from fly ash. The device comprises an ash bucket supported by a supporting frame, a high-temperature ash discharging valve mounted at the bottom of the ash bucket, an air pipe is mounted on one side of the ash bucket, dusty air flow enters the ash bucket from the air pipe, a lower tank body is mounted at the top of the ash bucket, an upper tank body is mounted at the top of the lower tank body through a flange, multiple uniformly distributed porous ceramic pipes are mounted at the top of the lower tank body through a porous plate, one side of the upper tank body is connected with a high-temperature fan through a pipeline, and clean air flow is in the pipeline. Dust is filtered in the corresponding tank body through the porous ceramic pipes, and purified air is discharged. The gas dust removal device used in the process for extracting aluminum oxide from fly ash can be used for high-temperature situations and situations where corrosive gas exists by means of the porous ceramic pipes with heat resistance and corrosion resistance, and the dust collection efficiency is unparallel to that of other dust collection techniques due to very high precision of the ceramic pipes in the dust removal process.