A small coal-fired industrial boiler was improved to save energy. By analyzing the boiler's problems like low efficiency and high carbon content in the flue gas, changes were made. Waste heat recovery, reconstruction of air chambers, and better water treatment were implemented. Training for managers and operators was also increased. As a result, the boiler's efficiency increased by 11.41%, coal consumption decreased by 9.9%, and output went up by 8.63%.