At present, the vast majority of onshore oil fields have been developed by water injection and polymer injection for a long time, which leads to the development of large pore channels or high permeability bands, and the ineffective and inefficient circulation of injected water becomes more and more serious. Aiming at the technical problems of poor plugging effect of conventional profile control and water plugging agent, taking the reservoir and fluid characteristics of Western B oilfield as the research object, this paper carried out the basic performance evaluation of starch graft copolymer gel, and studied the mechanism and analysis of oil and water control effect under different factors such as injection, plugging and different influencing factors. The results showed that the initial viscosity of starch graft copolymer gel was low, and the injection was good. However, the gel environment was seriously affected by gelatin. The larger the gelatin space, the higher the gelation strength. The sealing ability of the high permeability core was stronger than that of the low permeability core. This phenomenon indicated that it had less damage to the medium low permeability reservoir and had a selective sealing effect to a certain extent. In addition, it was found that the starch graft copolymer gel was not injected with PV, the more the better, there was a reasonable range. The highest recovery rate was obtained at 0.1PV, which indicated that with the increase of gel dosage, the damage to the medium and low permeability increased, but it was not conducive to the occurrence of fluid diversion. With the increase of PV number injected into the slug, the oil recovery increases gradually, but the increase decreases gradually, and the "output / input" ratio decreases gradually. The injection timing and core heterogeneity of starch graft copolymer gel also have an effect on the effect of increasing oil and precipitation. The earlier the injection time is, the weaker the degree of heterogeneity is, the better the plugging effect is, and the higher the final recovery rate is.