Three kinds of oilfield-used cross-linked polymer system (gel, cross-linked polymer microspheres and cross-linked polymer solution) were investigated.The progress of the three systems was summarized and the comparisons among them were carried out.The gel system has high blocking strength,but it cost a lot; cross-linked microspheres can go to the deep deformation, however, its blocking strength is weak;cross-linked polymer solution had low viscosity, but it can not be prepared with sewage and can only be injected at low concentration.