The invention discloses an environment-friendly submarine cable inner sheathing material with multiple protection effects and a preparation method of the inner sheathing material. The environment-friendly submarine cable inner sheathing material is prepared from components in parts by weight as follows: 68-88 parts of high-density polyethylene, 35-40 parts of fluorinated acrylate, 5-10 parts of a marine borer preventive agent, 20-30 parts of nano montmorillonite, 25-35 parts of mixed fibers, 1-5 parts of an antioxidant, 3-6 parts of nonylphenoxyacetic acid, 5-8 parts of eucommia rubber and 10-15 parts of tribehenin. By means of scientific formula design and a reasonable preparation process, the inner sheathing material integrates high strength, watertightness, fatigue resistance, high intensity and other protection functions, achieves the purpose that one protective layer replaces multiple protective layers and is non-toxic and environment-friendly, the radial size of a submarine cable is reduced, the cost is reduced, great convenience is brought to production, use and overhaul of the submarine cable, and the market prospect is wide.