Abstract: In the process of water flooding development in Bohai A oilfield, the phenomenon of rising pressure and insufficient injection gradually appeared. On the basis of investigation and analysis of the water quality and injection pressure data, the plugging mechanism of water injectors has been studied. The reasons for the pressure rising of injectors wellhead pressure were found out from the aspects of excessive water injection quality, scaling and corrosion leading to blockage, compatibility analysis, particle migration and sand production. And then, the experimental research on the plugging removal technique of water injectors was carried out. The results showed that the solids, median particle sizes and oil content in the injected water exceeded the standard, which caused blockage. Dissolved oxygen content, total iron content, bacteria and so on exceed the standard, resulting in scaling and corrosion pipeline in the process of water injection, leading to water injectors blockage. The compound acid system can effectively remove plugging and increase oil production, which can provide reliable technical support for the plugging removal and increase oil production in A oilfield.