Abstract: In the oilfield with a high salinity of injected water or formation water, the effect of polymer profile control and displacement agent is poor. To address this issue, a profile control and displacement system of “sodium silicate + dispersant” was designed. Together with calcium and magnesium ions in injected water or formation water, precipitated particles with a minimum particle size of less than 100 nm could be rapidly formed. Adjusting the concentration ratio of sodium silicate to dispersant could change the agglomeration degree of precipitated particles making the initial particle size controllable within 60.4 nm–3.85 μm, and controlling the dispersion time within 2–144 h which is feasible to accommodate reservoirs with different permeability. After the aggregation of precipitated particles, the final particle size of aggregates exceeded 70 μm, which could effectively block high-permeability channels and achieve deep fluid flow steering. The profile control and displacement system was tested in the P8 injection and production well group of an oilfield in the South China Sea. The salinity of injected water in this well group was 34 g/L, and the average injection pressure increased 2.9 MPa after 192 days of continuous injection of the precipitated particle profile control and displacement system. The water cut of the two affected wells was reduced by 4.6 and 17.8 percentage points, respectively, resulting in a cumulative oil gain of over 6 200 m³,with a valid period longer than 4 months. The research and field test show that the designed precipitated particle profile control and displacement system can solve the problem of poor profile control and displacement effects in oilfields with high salinity of injected water and provide technical support for oilfields with high salinity of injected water.