The present invention relates to an apparatus for treating high-temperature wastewater using a membrane distillation process, which comprises: a membrane distillation process for separating the high-temperature wastewater into high-temperature wastewater concentrated water and produced water by the difference of water vapor pressure generated by the temperature difference of the high-temperature wastewater and a cooling fluid; and a reverse osmosis membrane for separating the produced water containing pure water and volatile pollutants into the pure water and the volatile pollutants. The apparatus for treating high-temperature wastewater using a membrane distillation process reduces the energy, and can reduce an amount of wastewater by returning the produced pure water (treated water) to a high-temperature wastewater generation source, a membrane distillation treated water side, and the like to be reused, or by being reused as surrounding processed water or residential water.
