Abstract: Since the 1970s, Chesapeake Bay, Baltic Sea, Seto Inland Sea and Tokyo Bay have carried out marine environmental pollution control, and taken a series of actions to reduce the import of nitrogen and phosphorus into the ocean. After more than 30 years, the total nitrogen and total phosphorus inputs in the above-mentioned sea areas decreased significantly, especially the total phosphorus input of Tokyo Bay decreased by more than 70%. However, the improvement of seawater quality is far less than the reduction of emission. The increase of water quality standards attainment in Chesapeake Bay was only about 15%. The decreases of total nitrogen and total phosphorus concentrations in Seto Inland Sea and Tokyo Bay were only about 30%. The overall treatment effect of Baltic Sea was even worse, and the concentrations of total nitrogen and total phosphorus in the water body have not decreased significantly. In comparison, the reductions of ammonia nitrogen, total nitrogen and total phosphorus in the direct discharge sources of Bohai Sea were enormous, especially since the 13th Five-Year Plan, the reduction rate has been more than 50%, of which ammonia nitrogen has been reduced by more than 90%. The areas with water quality worse than Seawater Quality Standard Grade Ⅲ and Grade Ⅳ have continued to decrease after reaching the peak in 2012, with a decrease rate of nearly 90%. It can be seen that the reduction of nitrogen and phosphorus and the improvement of water quality in Bohai Sea were far higher than those in the above mentioned major international semi-closed sea areas, and the battle of comprehensive management of Bohai Sea has achieved remarkable results.