The invention discloses a suspended algae growing device and aims to provide the suspended algae growing device. According to the suspended algae growing device, the suspension depth of an algal reef can be controlled and the algal reel is enabled to multiply on the middle layer, an upper-middle layer and the lower-middle layer of a water area; in addition, algae attached to the algal reef are damaged caused by vertical violent floating of the suspended algal reef due to heavier sea wave fluctuation can be effectively avoided. The suspended algae growing device comprises a buoyancy device and an algal reef support body suspended below the buoyancy device through a connecting rope; the algal reef support body comprises a downward-recessed hemispheric support frame and a plurality of algae attaching base blocks arranged on the downward-recessed hemispheric support frame; a rope passing through hole is formed in each algae attaching base block; besides, a mounting rope is arranged in each rope passing through hole in each algae attaching base block; each algae attaching base block is fixed on the downward-recessed hemispheric support frame through each mounting rope.