The cross-linked polymer microspheres was synthesized by the methods of inverse emulsion polymerization,and the microspheres morphology,compatibility,sealing and oil properties of the dispersed system were studied.The results of SEM and TEM showed that the diameter of microspheres was in range of 100—200 nm after soaked with water for 10 d.Moreover,the cross-linked polymer microspheres possessed good salt tolerance and could plug the millipore filtration effectively.The results of block experiment in the sand tube with the multi-point manometry showed that the cross-linked polymer microspheres system could flow into the deep sand tube and play an effective role in blocking.The oil displacement experiments on parallel sand cores showed that after injecting 3 PV crosslinked polymer microspheres system with the mass fraction of 0.04%,prepared with oilfield simulation water,the oil recovery of the high,low permeability core with gas permeability of 2.0 μm2 and 0.5 μm2,respectively,could be enhanced by 21.42% and 42.69% based on the water flooding(61.61% and 0),respectively.