Offshore deep water taking device and method

The invention discloses an offshore deep water taking device and method, and belongs to the technical field of deep sea culture. Comprising a movable water taking pipe, a water taking well, a water taking pipe lifting device, a transition cabin, a sea valve, a deep-layer water taking grid, a middle-layer water taking grid, a shallow-layer water taking grid, a bottom water taking grid, transition cabin side holes and a water retaining partition plate. The water retaining partition plate is connected to the movable water taking pipe and located above or below the middle-layer water taking grating, and the water retaining partition plate is used for controlling opening and closing of the middle-layer water taking grating. By adjusting the height of the movable water taking pipe and the position of the water retaining partition plate of the middle water inlet, deep sea water flows to a sea water pump suction port through the water taking pipe, a transition cabin located at the bottom of the ship, a sea valve and