Compared with the onshore oilfield，Bohai Oilfield has great differences in reservoir geological characteristics，injection-production parameters and completion methods. In order to solve the technical problem of the fluid channeling in Bohai Oilfield，the experimental study on the composition selection and performance evaluation of the plugging agent was carried out based on the reservoir characteristics and fluid properties in Bohai Oilfield. The results show that the plugging agent is a dark gray compact solid，which consists of main agent，curing agent，thickener and retarder. It is a kind of plugging agents for large-size prefenrential channels which have the characteristics of high compressive strength and low permeability. Little correlation between total mineralization degree of the solvent and curing time，however，the CO32- and HCO3- in the solvent are beneficial to prolong the curing time. From the technical and economic point of view，the mass fraction of main agents is no less than 30% and the mass fraction of retarder ranges from 0.05% to 0.1%. Construction time can met the requirements by adjusting the the mass fraction of the retarder. When the formula of the plugging agent is made up of “thickener 5% + curing agent 0.15% + retarder 0.1% + main agent 30%”，the curing time is about 20 h.