A bottom ash discharging device for a coal-fired boiler including: a clinker case, installed between a bottom ash hopper outlet of the coal-fired boiler and a bottom ash conveyer, an impact bar including a plurality of heat-resistant metal rods supporting inside the clinker case, a clinker crusher, installed above the impact bar for crushing the clinker, and a guiding device, installed between the bottom ash hopper outlet and the clinker crusher for limiting the clinker to drop into the clinker crushing area of the clinker crusher. The bottom ash discharging device ensures that the clinkers drop from the bottom ash hopper outlet to the rear area of the clinker crusher, and that the impact bar can be replaced and repaired without stopping the coal-fired boiler.