Abstract: Salification is observed on the turbine blades of Dalate Power Plant Phase IV Project in overhauls. The power plant is equipped with two 600-MW coal-fired, direct air-cooling units. The analysis indicates that it mainly results from the poor effect of silicon washing during the tuning stage and the low pH value of the feedwater during the operation. Therefore, an improved operation condition for chemical water treatment is determined, including the water treatment mode changed from the original AVT (R) to AVT (O). Through boiler thermal chemical tests, a series of improvement measures is developed and adopted in the operation. A magnet remover is also installed in the condenser exhaust device, which improves the water vapor quality significantly. The acceptable rate of the water vapor quality of the two units has been raised from 92.3% and 90.2% to 99.7% and 99.2% respectively.