In this article, steel slag, desulfurization slag of molten iron during steelmaking, and red iron oxide in cold rolling were used as coal-burning additives respectively. The effect of waste slag on coal combustion was investigated by tests on a bench-scale fluidized bed with analyzer for the composition of flue gas. The results indicated that the moderate amounts of industrial waste slag, which were used as coal-burning additives, played a catalytic role in coal combustion, desulfurization, and denitrification, and it was advantageous to the resources recycling.