The structure of the door leaf, from the outside to the inside, is as follows: the first layer (door panel) is made of 1.2mm stainless steel plate or high-quality steel plate, the second layer is made of 3.0mm high-quality steel plate, the third layer is made of 30mm thick anti drilling and anti cutting alloy mixed material, the fourth layer is made of 2.0mm high-quality steel plate, the fifth layer is made of 1.2mm stainless steel plate, and the filling material is fireproof material. The inner and outer layers of the door leaf are made of 1.2mm stainless steel plate with a nominal thickness, and the filling material is fireproof cotton. There is a 1.2mm thick U-shaped groove skeleton around the door leaf, and a 1.2mm thick U-shaped skeleton in the middle layer. Three movable door bolts with a diameter of Φ 22.0MM and an effective expansion length of 18.0mm are used. A 5mm thick reinforced protective steel plate is installed at the lock installation site with the lock hole as the center within a radius of not less than 100MM.