Abstract: A method for treating an exhaust gas which includes leading a coal-fired exhaust gas to a dry denitrating device, removing oxides of nitrogen from the exhaust gas in the device, leading the exhaust gas to a dry electric dust collector and a wet waste smoke desulfurizing device disposed at downstream positions, and removing dust from the exhaust gas in these devices. A sodium compound containing solution is sprayed into the exhaust gas flowing between the dry denitrating device and the dry electric dust collector thereby increasing the efficiency of the dust collector, and the resulting dry solids are then collected together with the dust by the dry electric dust collector.