The invention discloses a fire-proof plate and a preparation method thereof. The fire-proof plate comprises closed cell perlite, volcanic ash, cement, asbestos fibers, talcum powder, sodium bicarbonate, calcium bicarbonate, barium sulfate, aluminum oxide C and water. The preparation method of the fire-proof plate includes the steps: uniformly mixing the closed cell perlite, the volcanic ash, the cement, the asbestos fibers, the barium sulfate and the aluminum oxide C to obtain a solid mixture A; adding the talcum powder into the water, adding the calcium bicarbonate and the sodium bicarbonateafter homogenization, and uniformly mixing the talcum powder, the calcium bicarbonate and the sodium bicarbonate to obtain liquid B; adding the liquid B into the solid mixture A and uniformly stirringthe liquid B and the solid mixture A to obtain mixed slurry; pouring the mixed slurry into a mould and performing standing, foaming and curing to obtain the fire-proof plate. The fire-proof plate isgood in heat insulation effect and suitable for manufacturing a fire-proof and heat insulation layer of special equipment such as a safety box and an ATM (automatic teller machine) and can effectivelyinsulate high temperature.