There are many production processes in thermal power plant, and the significance of energy saving and consumption reduction is important for every process, especially flue gas desulfurization system. This paper studied the impact of entrance negative pressure of booster fan on the total power consumption of induced draft fan and booster fan with the same boiler furnace negative pressure in the unit operation process. The results show that the total power consumption of induced draft fan and booster decreases with an increase in entrance negative pressure of booster fan. The research results can accumulate the experience of energy conservation and consumption reduction for thermal power plants, and adjustment the direction for the unit operation.