A totally enclosed flexible deep water enclosure can effectively separate open water body. The main body comprises a flexible bar shape floating body, a cork rope, a wall cloth, a ground rope, and a stone dragon. The stone dragon is buried in a sealed close bottom end of a silt layer, and the flexible bar shape floating body floats on the water to form separation. A mooring cable is used for fixing the ground rope on two under water wood piles at two sides, preserving degree relaxation in the vertical and horizontal directions. An under water anchoring mooring cable, the ground rope, a wall cloth longitudinal stiffening rib, and the cork rope constitutes the network-shape mechanics structure of the enclosure. The flexible bar shape floating body uses a flue to wrap a flexible closed-hole foam plastic strip, and the outside is protected by a changeable coating for structural durability. The enclosure subsections are connected by zipper fashion blanket stitches, convenient for processing, transportation, installation, dissembling, maintenance, and reuse, and can be used for contemporary separation of part water areas of the open water body, such as the boundary control of water surface project area, the separation and diversion of polluted water mass. The invention is suitable for natural conditions such as deep water (10m above), storm, water current, water level fluctuating, with the service life of 5-10 years.