The invention provides a method for preparing an insulation board. The method comprises the following steps: firstly, adding 4,4'-
diaminodiphenyl ether into dimethyl fomamide to prepare
mixed solution; mixing
sepiolite powder and glass beads, adding the mixture into the
mixed solution, uniformly stirring to obtain a mixture; respectively adding
triethylamine and aceticanhydride into the mixture, and adding 3,3',4,4'-
benzophenone tetracarboxylic dianhydride into the mixture for reaction to prepare a blend; and demolding the blend after the blend is extruded in a mould, and naturally cooling the blend to
room temperature to obtain the insulation board. In the method, the
sepiolite powder and the glass beads serving as inorganic phases and
polyimide serving as an organic phase are adopted to prepare the insulation board which is high-temperature resistant and has long service life. Compared with common insulation materials, by sufficiently utilizing the advantages of
corrosion resistance, light weight, low heat
conductivity of the
sepiolite powder and the glass beads, and high
temperature resistance, water prevention, high adhesiveness and the like of the
polyimide, the material has the advantages of low heat
conductivity, light weight, acid and alkali resistance,
corrosion resistance, wide application temperature range and the like, thereby having great market prospect.