The invention discloses a manufacturing method and a coating of a glass fiber fire blanket. A water-soluble mixed material is adopted to coat glass fiber base cloth in a dipping coating mode, so that a layer of dense fireproof coating is formed on the surface of the glass fiber base cloth, the surface of the coated glass fiber fire blanket is soft and airtight, flame can be isolated from fire, and thus the purpose of fire extinguishment is achieved. Meanwhile people escaping from fire can be protected by the glass fiber fire blanket as human bodies are prevented from damage caused by flame. When being used as a fireproof curtain, the glass fiber fire blanket can effectively prevent diffusion of flame, and has the characteristic of wide use range.