In order to meet the technical requirement of deep liquid flow steering in Bohai oilfield，the expansibility of two kinds of polymer microspheres in injected water and porous media was studied，as well as the injection capacity and plugging performance in long rock core by means of laser particle sizer，biomicroscope and core displacement experiment. The results showed that after 8 days of slow expansion in simulated injected water，the average particle size of microsphere A increased from 0.59 μm to 2.21 μm and that of microsphere B increased from 9.18 μm to 31.40 μm. After 7 days of slow expansion in porous media，the injection pressure increased significantly，showing the same good slow expansion effect. The microsphere could enter into the deep part of reservoir during injection process. The two microspheres had good transport and migration performance on the core with long of 300 cm and permeability of 1000 × 10^-3 μm² . After different time of hydration and expansion，the plugging rate of core increased significantly. After 7 days，the average plugging rate of microsphere B and microsphere A was 55.65% and 41.68% respectively. The closer to injection end，the higher plugging rate was. However，some microspheres with large particle size would stay at the end face of the core，resulting in the end face clogging and injection pressure loss of more than 40%.