The invention discloses a metal magnesium carbon thermal reduction process and device. The process comprises the following steps that a magnesium-containing raw material, a carbon-containing reducingagent and a catalyst are used as raw materials, the raw materials are subjected to uniform mixing and forming, under certain temperature and vacuum degree conditions, current is directly conducted atthe two ends of a formed sample, and the current is controlled to carry out power-on reduction reaction, and the cooling is carried out to obtain the metal magnesium after the reaction is finished. The device comprises a reactor, a positive electrode, a negative electrode, a position buffer and a sealing cover, wherein the reactor is used for performing a metal magnesium reduction reaction, the positive electrode and the negative electrode are used for directly applying current to the reaction raw material formed parts, the position buffer is used for regulating the positive and negative electrodes, and the sealing cover is used for sealing the reactor. The process and device overcome the series of problems such as high reduction temperature, long reduction time, reversible reaction and the like of an existing carbon thermal method metal magnesium, the temperature of the reduction device can be greatly reduced, the metal magnesium can be initially reduced at room temperature, the reduction speed of the metal magnesium is greatly improved, and the process is green and environmentally friendly.