A crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater, comprising an active component core material capable of binding corrosive ions, a wall layer, and an interface improvement layer, wherein the active component core material capable of binding corrosive ions is a mixture of a calcium-containing inorganic substance, an aluminum-containing inorganic substance, and a macromolecule water-absorbent resin;
- the wall layer is a polymethyl methacrylate (PMMA) layer, which covers the active component core material capable of binding corrosive ions;
- and the interface improvement layer is a cement layer.