The invention discloses an STP ultra-thin vacuum heat insulation plate for a building external wall, which comprises a composite inorganic
fiber core material, a heat insulation
coating and a high-barrier
composite film; the heat insulation
coating coats on the outer surface of the composite inorganic
fiber core material, the composite inorganic
fiber core material is arranged in the high-barriercomposite film, the composite inorganic fiber core material is provided with a
honeycomb-shaped through hole, the
honeycomb-shaped through hole is filled with glass-shaped micro-beads, the
honeycomb-shaped through hole is an inclined hole, and the inclination angle is 30-45 degrees. The invention also discloses a preparation method of the STP ultra-thin vacuum heat insulation plate for the building external wall. According to the invention, the heat insulation
coating coats on the core material of the STP ultra-thin vacuum heat insulation plate, so that the plate has super-strong heat insulation effect, meanwhile, the honeycomb-shaped inclined through hole is arranged on the heat insulation plate, which ensures the stable foundation of the heat insulation plate, and the air flow is resisted, so that the air is not easy to form
convection, and the possibility of
convective heat transfer is reduced, and the heat preservation effect of the heat insulation plate is ensured.