The invention relates to a macrophytic algae aquaculture facility suitable for open type deep waters, in particular to an adjustable deep sea algae aquaculture floating bed, which substantially comprises a main anchor cable, a sea algae aquaculture floating bed and a weight system, wherein a mooring rope of the main anchor cable consists of a main float ball, a center circle, a chain ring, a lower circle, a rotating ring and a dropstone, and the sea algae aquaculture floating bed comprises a buoyancy framework, a bottom net, a purse net, a center circle, an oblique stay cord, a weight system and a guide plate. The adjustable deep sea algae aquaculture floating bed is a movable type floating bed frame, wherein the bottom portion of the adjustable deep sea algae aquaculture floating bed is provided with the bottom net, the middle portion of the bottom net is provided with a round iron ring, and the periphery of the movable type floating bed frame is inwardly obliquely provided with a circle of purse net. The weight system comprises a weight hanging rack, a weight block and a position card bolt. The adjustable deep sea algae aquaculture floating bed uses a double-buoyancy system, and can be guaranteed in an upright posture underwater through own bigger buoyancy of the movable type floating bed frame, can be accurately fixed on a scheduled water layer through a buoyancy system of the main anchor cable, and is more convenient to adjust the scheduled water layer by integrally arranging the adjustable deep sea algae aquaculture floating bed and the weight system in a micro buoyancy state.