Abstract: Due to the long-term scouring by water flow, the effective buried depth of the Donghai Bridge pile foundation has been diminishing year by year, thus leading to the decreasing of the pile foundation stability and even to the endangering of the entire building safety. For the protection project of bridge pile groups, the stabilized soil slurry ratio is investigated and determined, the high flow stabilized soil protection construction is successfully completed and the underwater pumping construction process and the outcomes and long-term protective effects of the stabilized soil protection construction are analyzed. The results indicate that with the increasing of curing agent dosage, the strength of the stabilized soil increases while its fluidity decreases, whereas with increasing in water content of the soil slurry, the strength of the stabilized soil decreases while its fluidity increases. The underwater high-definition sonar is used for observing real-time the relative positions between the underwater pile foundations and the pumping pipe. It is found that the underwater ejection distance of the stabilized soil slurry is approximately 2.5 meters and its flowing distance and width are both over 3 meters. The lowest point of the centre-line projection of Pier PM123 has upraised by approximately 4.3 meters and that of Pier PM230 by approximately 5.4 meters. Obviously, the construction of the stabilized soil protection can effectively backfill the gaps of pile groups and the depressions at the bottom, forming a smooth stabilized soil protective layer with excellent erosion resistance and long-term durability. This engineering practice can accumulate experiences and provide data support and technical reference for similar projects.