The invention discloses an environment-friendly coating. The thermal insulating coating is prepared from raw materials in parts by mass as follows: 50 parts of calcium silicate powder, 20-40 parts of filler, 10-25 parts of a binding agent, 10-20 parts of silicon dioxide aerogel, 5-10 parts of polyimide powder, 8-15 parts of polyurethane prepolymers, 4-8 parts of a curing agent and 0.5-2 parts of an additive. The prepared calcium silicate thermal insulating coating is environment-friendly, has good adhesive force and thermal insulating performance and is a green building material with great development potential.