Abstract: A high-viscosity polymer was developed in order to adjust the profile of heterogeneous offshore oilfields in the middle-high water cut period. Performance advantages were achieved by taking acrylamide (AM) as the main agent and N, N methylenebisacrylamide (MBA) as the crosslinker. This polymer can be processed by the grinding control technology to obtain a dispersed copolymer particle system. The experimental results showed that the grinding rate and grinding time had a large impact on the particle size distribution for the given monomer mass fraction (5%) and the AM/MBA mass ratio of 250 to 1. The results of plugging and migration experiment under simulated formation conditions indicated that the dispersed copolymer particle system had good injectability, deep migration ability and plugging performance. For the given dosage, the plugging ability of dispersed copolymer particles was significantly better than that of the polymer gel. The research suggested that the particle size distribution of this system was wide and controllable in the nanometer to micrometer level, making online injection possible. The system has the advantages of simple formulating process, low cost, temperature resistance and environmental protection, etc. It possesses good applicability in offshore oilfields for the profile control in the middle-high water cut period, and can be promoted and applied in oilfields.