Abstract: The advantages and disadvantages of a typical semi-dry flue gas desulfurization (FGD) method are analyzed and a novel semi-dry FGD method of simple and compact system with high efficiency is firstly put forward, named multi-fluid alkaline spray generator FGD method. The results show that the colliding activation efficiency between the sorbent particles and the spray water droplets in the prefixed alkaline spray generator may reach about 70%, which is significantly higher than the 25% colliding activation efficiency in in-duct injection FGD. And SO2 removal efficiency reaches 70%, higher than that of in-duct injection FGD at the same conditions. The study confirms it is a new simple compact and highly-efficient semi-dry FGD method.