The invention discloses a fireproof A1 level inorganic interior and exterior wall heat insulation board and a production method thereof. The heat insulation board comprises 60-80wt% of Portland cement, 0-21wt% of slag powder, 10-35wt% of fly ash, 1.4-2wt% of a waterproof agent, 1-2wt% of iron oxide black, 0.1-0.34wt% of fiber, 0.01-0.8wt% of cellulose, 0.3-1.2wt% of an early strength agent, and 7-12wt% of a foaming agent. The invention also provides a production method of the fireproof A1 level inorganic interior and exterior wall heat insulation board. The heat insulation board is produced by adopting inorganic materials, so the heat insulation board has the advantages of certain compressive strength and tensile strength, light weight, water and fire proofing, corrosion proofing, sound insulation, heat insulation, non-toxicity, no peculiar smell, small heat conduction coefficient, freeze and thaw resistance, and good weather ability, has same life with a unit building, and is a most rational exterior heat insulation material. Repeated construction, repeated investment and repeated pollution are avoided in the invention. The heat insulation board and the production method have good economic, social and environmentally friendly benefits.