A method for preparing artificial graphite comprising: preparing heavy oil, forming coke from the heavy oil through continuous coking reaction such that the coke has a plurality of mesophase domains, wherein a size of the mesophase domains ranges between 1 and 30 μm by polarizing microscope analysis; and processing the coke formed by step sequentially by pre-burning carbonization treatment, grinding classification, high-temperature carbonization treatment and graphitization treatment to form polycrystalline artificial graphite from the coke; wherein step comprises: transporting the heavy oil into a heating furnace, and heating the heavy oil under conditions of a heating temperature ranging between 480 ° C and 520 ° C at a pressure ranging between 0.18 Mpa and 0.22 Mpa for a heating time ranging between 0.01 hour and 0.02 hour, and simultaneously transporting water into the heating furnace for heating to produce water vapor; transporting the heated heavy oil at a high flow speed of 0.02 m 3 /s to 0.03 m 3 /s in the presence of the water vapor by a delivery pipe to a coking tower; and causing the heated heavy oil to crack and condensation polymerize under conditions of a reaction temperature ranging between 470 ° C and 520 ° C at a pressure ranging between 0.18 Mpa and 0.22 Mpa for a reaction time ranging between 16 hours and 24 hours to form coke; wherein in step, a calcining temperature of the pre-burning carbonization treatment ranges between 800 ° C and 1000 ° C, and a calcining time ranges between 4 hours and 16 hours. preparing heavy oil, forming coke from the heavy oil through continuous coking reaction such that the coke has a plurality of mesophase domains, wherein a size of the mesophase domains ranges between 1 and 30 μm by polarizing microscope analysis; and processing the coke formed by step sequentially by pre-burning carbonization treatment, grinding classification, high-temperature carbonization treatment and graphitization treatment to form polycrystalline artificial graphite from the coke; wherein step comprises: transporting the heavy oil into a heating furnace, and heating the heavy oil under conditions of a heating temperature ranging between 480 ° C and 520 ° C at a pressure ranging between 0.18 Mpa and 0.22 Mpa for a heating time ranging between 0.01 hour and 0.02 hour, and simultaneously transporting water into the heating furnace for heating to produce water vapor; transporting the heated heavy oil at a high flow speed of 0.02 m 3 /s to 0.03 m 3 /s in the presence of the water vapor by a delivery pipe to a coking tower; and causing the heated heavy oil to crack and condensation polymerize under conditions of a reaction temperature ranging between 470 ° C and 520 ° C at a pressure ranging between 0.18 Mpa and 0.22 Mpa for a reaction time ranging between 16 hours and 24 hours to form coke; wherein in step, a calcining temperature of the pre-burning carbonization treatment ranges between 800 ° C and 1000 ° C, and a calcining time ranges between 4 hours and 16 hours. transporting the heavy oil into a heating furnace, and heating the heavy oil under conditions of a heating temperature ranging between 480 ° C and 520 ° C at a pressure ranging between 0.18 Mpa and 0.22 Mpa for a heating time ranging between 0.01 hour and 0.02 hour, and simultaneously transporting water into the heating furnace for heating to produce water vapor; transporting the heated heavy oil at a high flow speed of 0.02 m 3 /s to 0.03 m 3 /s in the presence of the water vapor by a delivery pipe to a coking tower; and causing the heated heavy oil to crack and condensation polymerize under conditions of a reaction temperature ranging between 470 ° C and 520 ° C at a pressure ranging between 0.18 Mpa and 0.22 Mpa for a reaction time ranging between 16 hours and 24 hours to form coke; wherein in step, a calcining temperature of the pre-burning carbonization treatment ranges between 800 ° C and 1000 ° C, and a calcining time ranges between 4 hours and 16 hours.