The invention discloses an A1-grade fireproof insulation mortar which is prepared from the raw materials of, by weight: common Portland cement, fly ash, expanded vermiculite, expanded glass micro-beads, re-dispersible latex powder, fiber, cellulose ether, and an air-entraining agent. According to the invention, glass micro-beads are adopted as a light aggregate, and the expanded vermiculite with excellent fireproof performance is doped in. Compared with a dry-mix insulation mortar light aggregate with expanded perlite and polystyrene particles, the defects of high water absorption, easy pulverization, high volume shrinkage rate in slurry stirring, and phenomena of product low post-stage strength and hollowing cracking, and the like of expanded perlite are overcome. Also, defects of high inflammability, poor fire retardant performance, harmful gas production under high temperature, low aging resistance, low weather resistance, high resilience during construction, and the like of organic materials such as EPS and XPS are overcome. With the mortar provided by the invention, insulation mortar comprehensive performances and construction performance are improved. On the basis of good safety, energy-saving and comfortableness are realized. With the mortar, building, human, and nature are harmonious and unified.