The invention belongs to the field of composite boards, and discloses a composite board integrating heat insulation and bearing and a preparation method thereof. The composite board comprises a hollowglass micro-bead layer and high-temperature-resistant composite boards located on the upper face and the lower face of the hollow glass micro-bead layer, and all the layers of the composite board arefixed through a plurality of bolts. The high-temperature-resistant composite boards and the bolts are made of the same materials which are a carbon/carbon composite material, a carbon fiber reinforced silicon carbide composite material, a carbon fiber reinforced molybdenum disilicide composite material, a carbon fiber reinforced zirconium diboride composite material, a carbon fiber reinforced zirconium dioxide composite material, a carbon fiber reinforced titanium diboride composite material, a carbon fiber reinforced silicon nitride composite material, a carbon fiber reinforced aluminum oxide composite material or a carbon fiber reinforced tungsten carbide composite material. The hollow glass micro-bead layer and the high-temperature-resistant composite boards are combined with each other, so that the properties of light weight, high strength and heat insulation of the hollow glass micro-beads and the excellent properties of low density, high temperature resistance, corrosion resistance, thermal shock resistance and the like of the high-temperature-resistant composite boards are brought into full play.