After long-term water injection and polymer injection development in Bohai L，S and J oilfields，the heterogeneity of reservoir is further enhanced. The polymer is retained in the reservoir，resulting in a significant decrease in liquid absorption capacity of the reservoir. Plugging removal is one of the most effective technical means to alleviate the current situation. In order to meet the needs of chemical flooding plugging removal technology in Bohai Sea，the plugging removal effect of compound plugging removal agent and scale dissolving agent composed of depolymerization agent，acid and chelating agent was evaluated. The influence and mechanism of injection mode，injection pressure and profile control measures on plugging removal effect were explored. The results showed that when the mass fraction of depolymerization agent composed of 1.0% ammonium persulfate and 0.5% inorganic corrosion inhibitor was 1.0% and the slug size was 0.05 PV，the permeability recovery rate of polymer-blocked core could reach 90.31%，indicating good depolymerization effect. When the mass fraction of scale dissolving agent composed of 0.54%citric acid and 5.46% chelating agent was 6.0% and 8.0%，the permeability recovery rate of three kinds of inorganic scale plugging cores was more than 80%，indicating good scale dissolution effect. Improving the injection rate of plugging removal agent could increase the injection pressure and improve the plugging removal effect. When the injection pressure increased to 3.0 times and 3.5 times the water flooding pressure，the recovery rate increased by 0.74 percentage point and 0.88 percentage point. However，after increasing the injection pressure，most of the liquid would still enter the high permeability part of reservoir，and then the increase of liquid absorption in low permeability layer was very limited，which would affect the plugging removal effect. Therefore，the combined operation technology of profile control and plugging removal was put forward. That is，profile control was carried out before plugging removal. Compared with simple plugging removal，when 0.3 PV and 0.6 PV inorganic gel profile control agent were injected，the recovery rate of profile control and plugging removal combined operation increased by 7.7 percentage points and 12.19 percentage points，respectively.