The invention discloses a graphitization furnace and a method for heat treatment of graphite powder by virtue of graphitization furnace. A plurality of graphite boxes, which are connected and communicated with one another, are arranged among symmetric electrodes arranged inside a furnace body of the graphitization furnace from a furnace head to a furnace tail, vent holes are formed in one surface, which is opposite to the side wall of the furnace body, of each graphite box, and vent pipes penetrate through the vent holes, extend to the outside of the side wall body and are connected with a purifying gas tank; each graphite box is formed by assembling graphite blocks made of a graphite material. The method for heat treatment of graphite powder comprises the steps of assembling a graphite box, distributing vent pipes, filling powder, sealing a cover, filling a thermal-insulation material, graphitizing by heating, introducing gas and purifying, cooling, discharging and the like. By virtue of the graphitization furnace and the corresponding method, graphite powder is subjected to heat treatment and purified so as to achieve the advantages of low energy consumption, high thermal efficiency and high yield; the product has the advantages of stable quality and high purity, the gas flow rate of the purifying gas is decreased, no protective gas such as nitrogen is used and thus negative impacts of nitrogen on the performance of products such as synthetic diamond or negative electrode materials of a lithium battery negative positive material are avoided.