Provided is a cabinet, which comprises a top cover, four tri-layer side walls and a tri-layer base. The top cover, the four tri-layer side walls and the tri-layer base are connected with and fixed to one another by aluminum extrusion fixing assemblies. The tri-layer structure includes an inner honeycomb panel, a middle strengthening assembly and an outer wall panel. The middle strengthening assembly is formed by a plurality of horizontal tension rods and a plurality of vertical tension rods intersecting. The inner honeycomb panel has a hexagonal-celled hollow geometric structure, which confers the panel with such properties as high pressure-endurable strength, light weight, excellent rigidity and high structural stability. In addition, the hexagonal hollow cells can also make the honeycomb panel capable of better thermal insulation by preventing the air flow.