Abstract: Preformed particle gel(PPG) enhanced polymer flooding is a new chemical flooding method which is suit to both serious heterogeneous reservoir and HT/HS reservoir based on PPG's insensitive to temperature and salinity and excellent profile control performance. Two tube sand pack core flooding tests conducted under HT/HS reservoir condition of Shengli oilfield indicate that the injection of PPG enhanced polymer system generates a significant fluid diversion, tetrad the heterogenous both within layer and between layers, and improve the swept volume substantially. The incremented oil recovery by 0.3Vp polymer flooding is only about 6.7%, while the recovery ratio increase of PPG enhanced polymer flooding slug with the same volume is up to 23.8%;0.2Vp additional PPG enhanced polymer flooding slug can further increase oil recovery 11.8% after the polymer flooding. It can be predicted that PPG enhanced polymer flooding will meet a broad potential in HT/HS and post-polymer flooding reservoirs.