Abstract: In the pressurized water reactor which uses ammonia to adjust the feedwater p H, the high PH control method is usually used to inhibit the flow accelerated corrosion（FAC）in the secondary system. But the increasing Ammonia concentration will shorten the lifetime of the resin in the steam generator blowdown system demineralizer, which will lead to the increasing of waste, heavy loading, and operation cost. By the ammonia-saturated operation test of the resin in the steam generator blowdown system demineralizer in Qinshan phase Ⅱ, we found that the ammonia-saturated operation is feasible; and it is an effective method to balance the demand of high PH value and the lifetime of demineralizer resin. And we prefer to use 2 demineralize systems together, one with ammonia-saturated operation and another one with hydrogen operation.