Much smoke is produced during the production of electric fused alumina, which causes serious environmental pollution. In order to evaluate its environmental impacts, the authors collected data from two groups of electric furnaces in Guizhou Province, being 3000 kVA and 7500 kVA respectively. According to forecasting calculation and analysis, it is shown that the environmental quality has been greatly improved after the dust removal by means of electric or sack methods, with air quality changed from Grade 3 to Grade 1. The composition of the corundum dusts is studied by chemical analysis, electron microscope analysis and X-ray analysis. It is shown that the corundum dusts are ultrafine granular gray powders consisting of glassy eutectics of O, Al, Si and K. There are also some potassium sulfate, corundum and limonite in the dust. A recycle technique of the dusts is also suggested.