It comprises a cabinet bottom, a top cover and side walls, as well as a rack, a spring leaf, an upper waveguide window, a lower waveguide window, a door cutter, a filter, a shielding glass, a perspective shielding glass door, a back door, a waveguide and bare-end racks, wherein the four racks are fixed on the inner side walls of the cabinet, and the bare-end racks are installed on the four racks; The upper waveguide window and the lower waveguide window are respectively arranged on the top cover and the bottom of the box; There is a door on the cabinet. It can be used to place computers and servers, prevent electromagnetic waves from harming people, effectively inhibit the leakage of electromagnetic information of computers, and prevent strong external electromagnetic interference from affecting the normal work of computers. The application frequency band is wide, which meets the requirements of national standard B or C and military standard B. ..