The invention discloses a formula of a fire retardance modified polyurethane insulation board. The formula comprises premixed polyether polyol, polymeric diphenylmethane diisocyanate and auxiliary agents, the premixed polyether polyol is a polyether/ polyester polyol polyhydroxy compound, the polymeric diphenylmethane diisocyanate is polyaryl polymethylene isocyanate, and the auxiliary agents comprise a catalytic agent, a foaming agent, a foam stabilizer, a cross-linking agent and fire retardants. The formula is characterized in that the fire retardants comprise a tungstate inorganic flame retardant and a nanometer aerogel silica inorganic flame retardant. The invention further relates to a production process of the fire retardance modified polyurethane insulation board. By means of the technical scheme, the formula and the process of the fire retardance modified polyurethane insulation board have the advantages that by means of the ammonium meta-tungstate (AMT) oriented tungsten inorganic flame retardant and the nanometer aerogel silica inorganic composite flame retardant, flame retardant properties of materials are effectively improved.