The invention discloses a computer hardware fixing device. The computer hardware fixing device comprises a fixing base, a groove is formed in the lower end face of the fixing base, and a supporting plate is arranged above the fixing base. The computer hardware fixing device is ingenious in structural arrangement and reasonable in layout, a computer hardware body is placed in a mounting box, a temperature sensor is used for measuring the temperature inside the mounting box, and when the temperature of the mounting box reaches a certain value, a motor is electrified to efficiently cool the interior of the mounting box; meanwhile, the supporting plate at the bottom of the mounting box is supported on the fixing base through compression springs, and vertical vibration is effectively reduced; besides, through vertical sleeves and telescopic rods in telescopic springs, the supporting rigidity of the compression springs is effectively guaranteed, the stability of the supporting plate is improved, besides, the left side of the mounting box is fixed to a lateral plate through connecting springs, horizontal vibration can be effectively alleviated, and when the mounting box needs to be dismantled, the mounting box is conveniently dismantled vertically through pulleys at the bottom and a sliding plate arranged at the right end of the supporting plate.