A multi-functional floating island made by degradable material is produced by the steps: collecting straw, immersing the straw with limewater about 15-25 hours, degreasing; after airing and drying, disintegrating the straw into scrappy through disintegrator; putting the scrappy into stirrer, adding polyvinyl acetate emulsion wood adhesive agent (white rubber), stirring uniformly, putting the stirred and mixed scrappy into mold, cooling and shaping, polishing, ripping edge, cooling, then preparing the floating island, the weight of the floating island per cubic centimeter is less than the specific gravity of water. Its advantages are: using farm crop straw and other agricultural crops excess stock preparing floating island material block, the floating island material block can used for cultivating water-loving plant, and for cultivating low-growing plant, also for high-growing ornamental plants with economic value.