Abstract: Reservoir properties have greatly changed in No.12 fault-block,Huzhuangji oilfield after the oilfield has been developed by waterflooding for about ten years.In this paper,two adjacent cored wells(Hu12-20 and HJ1),drilled at the pre-and post-waterflooding,are selected as "research window".Dynamic variation of reservoir is explained from the view of point of reservoir physical properties,intraformational and interlayer heterogeneities and reservoir micropore structure,which will provide important geological basis for improving oilfield development effect.