The invention discloses a cooling device of a reinforced tri-proof computer. The cooling device is installed in a computer reinforced housing and positioned at one side of a circuit board. The coolingdevice at least comprises a group of a heat exchange net sheet and a middle heat exchange plate. The heat exchange net sheet is positioned at two ends of the middle heat exchange plate. The middle heat exchange plate is fixed on the bottom wall in the computer reinforced housing by using an installation fixing component. The heat exchange net sheet is fixed in the computer reinforced housing or on the middle heat exchange plate by using multiple heat exchange copper alloy frames. The cooling device is capable of improving the cooling effect, and satisfying the requirements of the reinforced tri-proof computer, and has the good severe environment adaptive capacity. A cooling fan of the cooling device is rotated in the ultra-high speed, so the cooling capability is improved. A cooling fin uses a combined net tube structure, so the heat exchange surface area is large, and the heat exchange effect is good. The fixing component of the cooling device has the good fixing effect, anti-knock effect, and cooling effect. The heat exchange plate of the cooling device is stable in structure, and strong in heat exchange capability, and is capable of greatly improving the cooling capability by coordinating with the heat exchange net sheet.