The invention relates to the technical field of concrete anticorrosion and aims at providing a geopolymer coating material for marine concrete protection. The coating material is prepared from the following raw material ingredients in parts by weight: 100 parts of aluminum silicate material, 10 to 20 parts of alkali activator, 50 to 200 parts of fine aggregate, 5 to 20 parts of water-soluble polymer, 0.2 to 0.5 part of fiber material, 3 to 5 parts of expanding agent, 0.5 to 2 parts of water reducing agent, 0.5 to 1 part of suspending agent, 0.5 to 1 part of coupling agent, 0.2 to 0.5 part of defoaming agent and 30 to 50 parts of water. The geopolymer coating material disclosed by the invention uses multiple safeguard measures, so that a shrinkage and crack performance of the polymer coating material is synergetically enhanced; the geopolymer coating material is compounded with an organic functional material, so that a dewatering function and an iontophoresis resistance function are enhanced; by means of optimizing a functional additive, a rheological property of the geopolymer coating material is improved, bubbles in slurry in a preparation process are eliminated, and a construction performance of the geopolymer coating material is enhanced.