A liquid immersion cooler includes a metal case, a soldering layer, a heat conduction layer, and a porous structure. The metal case has a heated surface and a cooling surface disposed on back of the heated surface. The soldering layer is laid on the cooling surface. The heat conduction layer is laid on the soldering layer. The porous structure is laid on the heat conduction layer. Therefore, the waste heat from an electronic heat source may be rapidly dissipated.