An offshore floating island, comprising a supporting structure and an island main body, wherein the bottom of the supporting structure is fixed at the seabed, and the island main body comprises one or two or more compartment bodies (11, 12); the upper part of the supporting structure is provided with a carrying part; the bottom of each compartment body (11, 12) is provided with a mounting part; the compartment body (11, 12) is of a cavity structure, and a filler is injected to the compartment body (11, 12) till the compartment body (11, 12) sinks to cause the mounting part to be in lock type clamping with the carrying part, so that the compartment body (11, 12) and the supporting structure are detachably connected; and each compartment body (11, 12) is at least partially higher than the sea surface after the compartment body (11, 12) and the supporting structure are assembled in place, the offshore floating island being characterized in that the supporting structure comprises an anchor rod and a hydraulic mechanism, wherein the upper ends of the anchor rod and the hydraulic mechanism are connected with the compartment bodies (11, 12), and the lower ends of the anchor rod and the hydraulic mechanism are fixed at the seabed; the hydraulic mechanism comprises a shell and a hydraulic telescopic rod; the hydraulic telescopic rod is located in the shell, and a telescopic end of the hydraulic telescopic rod abuts against the bottoms of the compartment bodies (11, 12) to push the compartment bodies (11, 12); the anchor rod is used to pull down the compartment bodies (11, 12); and the anchor rod is provided with a buffer piece that telescopically deforms under the action of an external force; the supporting structure further comprises a protective housing; the protective housing covers the anchor rod and the hydraulic mechanism inside; the protective housing is a hood body of a corrugated structure and can telescopically deform under the action of the external force. the bottom of the supporting structure is fixed at the seabed, and the island main body comprises one or two or more compartment bodies (11, 12); the upper part of the supporting structure is provided with a carrying part; the bottom of each compartment body (11, 12) is provided with a mounting part; the compartment body (11, 12) is of a cavity structure, and a filler is injected to the compartment body (11, 12) till the compartment body (11, 12) sinks to cause the mounting part to be in lock type clamping with the carrying part, so that the compartment body (11, 12) and the supporting structure are detachably connected; and each compartment body (11, 12) is at least partially higher than the sea surface after the compartment body (11, 12) and the supporting structure are assembled in place, the offshore floating island being characterized in that the supporting structure comprises an anchor rod and a hydraulic mechanism, wherein the upper ends of the anchor rod and the hydraulic mechanism are connected with the compartment bodies (11, 12), and the lower ends of the anchor rod and the hydraulic mechanism are fixed at the seabed; the hydraulic mechanism comprises a shell and a hydraulic telescopic rod; the hydraulic telescopic rod is located in the shell, and a telescopic end of the hydraulic telescopic rod abuts against the bottoms of the compartment bodies (11, 12) to push the compartment bodies (11, 12); the anchor rod is used to pull down the compartment bodies (11, 12); and the anchor rod is provided with a buffer piece that telescopically deforms under the action of an external force; the supporting structure further comprises a protective housing; the protective housing covers the anchor rod and the hydraulic mechanism inside; the protective housing is a hood body of a corrugated structure and can telescopically deform under the action of the external force.