The invention relates to a radiation-proof high-integrity container and a preparation method thereof. The radiation-proof high-integrity container comprises an outer wall, a middle shielding layer andan inner wall, the outer wall and the inner wall are made of a material A, and the middle shielding layer is made of a material B, wherein the material A comprises the following components in parts by weight: 100 parts of a first thermoplastic polymer, 0.3-1.2 parts of a first antioxidant, 0.5-3 part of a first cross-linking agent and 1-20 parts of a first additive; and the material B comprises the following components in parts by weight: 100 parts of a second thermoplastic polymer, 0.3-1.2 parts of a second antioxidant, 0.3-2 part of a second cross-linking agent, 2-5 parts of a foaming agent, 60-100 parts of an anti-radiation agent 1-20 parts of a second additive. The material A and the material B in the radiation-proof high-integrity container have good compatibility; and the anti-radiation agent is selected from two or more of tungsten, lead, bismuth, heavy metal salt, heavy metal oxide, rare earth oxide, a compound containing a lithium element and a compound containing a boron element.