The invention discloses high-temperature resistant release paper which is prepared from the following raw materials in parts by weight: 70-100 parts of low-density polyethylene plastic particles, 10-50 parts of high-density polyethylene plastic particles, 1-5 parts of separant solvent-type silicone oil, 3-10 parts of crosslinking agents, 2-5 parts of stabilizing agents and 1-5 parts of catalysts. The invention also discloses a preparation process of the high-temperature resistant release paper. Given the shortcomings of the original technology, the density of the low-density polyethylene is increased, and the coating density is increased along; therefore, the water vapor transmission rate is reduced, the brightness, stiffness and tensile strength of the flame retardant paper are improved, and high-quality flame retardant paper is obtained; meanwhile, the surface is coated with the separant solvent-type silicone oil, and thus the stripping force of the release paper is less than or equal to 3g; by improving the raw materials and process, the flame retardant effect and stability of the release paper are greatly improved.