Based on long-time data of base line, water depth, geological structure, satellite image and hydrology, the issue of the Bohai Sea Closing was discussed in this paper. The GPS observation results clearly show that the Bohai Sea is in the process of tectonic contraction. The geologic record and results of long-term tidal stations show that the sea level of the Bohai Sea is falling. With the Bohai Sea circulation change, more substances of the Yellow River may deposit towards the Bohai Sea, as a result, the closing rate of the Bohai Sea could also be accelerated. The remote effect of the Himalayas uplift causes tectonic shrinkage of the Bohai Sea, and a large number of deposits are carried into the Bohai Sea by Yellow River, thus fundamentally causing the closing of the Bohai Sea.