The invention provides an insulation material having air purifying function and a preparation method thereof, which relate to the field of the insulation material. The insulation material comprises the following raw materials in parts by weight: 14-20 parts of calcium silicate powder, 10-28 parts of granite powder, 15-17 parts of polyurethane, 17-23 parts of alumina silicate powder, 5-9 parts of magnesium oxide, 7-13 parts of mineral wool, 4-8 parts of polyester fiber, 21-35 parts of bamboo charcoal, 7-13 parts of bentonite, 9-13 parts of meerschaum powder, 15-19 parts of phenolic foam, 11-31 parts of vermiculite, 15-21 parts of waste polyethylene foamed plastic, 9-15 parts of boron fiber, 13-21 parts of polyacrylonitrile fiber, 27-35 parts of cement, 0.2-0.4 parts of an air-entrainer, 0.1-0.7 parts of a delayed coagulant, 0.1-0.3 parts of a heat stabilizer, 0.3-0.7 parts of a water reducer, 0.2-0.6 parts of a foaming agent, and 4-8 parts of water. The preparation method comprises the following steps: 1) raw material weighing; 2) roasting; 3) crushing; 4) stirring; 5) pressurization moulding; and 6) drying. The insulation material has the advantages of high intensity, good heat insulation performance, environmental protection and energy saving.