The invention discloses a preparation method of a battery-grade 
graphite-
activated carbon composite material. The preparation method comprises the steps that 1, 
plant raw materials are washed clean with water and then contained in a 
metal tank, the 
metal tank is sealed and put into a 
muffle furnace, heating is conducted at the constant temperature of 450 DEG C to 650 DEG C, the temperature is naturally decreased to 
room temperature, and black 
solid activated carbon is obtained; 2, the obtained black 
solid activated carbon and 
graphite are put into a ball milling tank according to the 
mass ratio of 3:1-1:1, an appropriate amount of 
hydrochloric acid with the concentration of 0.2 M to1.0 M, an appropriate amount of 
sulfuric acid with the concentration of 0.1 M to 0.5 M, an appropriate amount of 
acetic acid with the concentration of 0.5 M to 1.2 M and an appropriate amount of water are sequentially added into the ball milling tank, ball milling is conducted for 0.5 hour to 2 hours under the condition that the ball-material ratio is equal to 1:10-1:20, and then 
acid washing and 
water washing are sequentially conducted, wherein 
sulfuric acid, 
hydrochloric acid and 
acetic acid are subjected to ball-milling washing three times to five times separately, and the water is subjected to ball-milling washing until the pH value of eluate is 6.8 to 7.2; 3, the washed 
graphite-activated carbon mixture is subjected to suction 
filtration and dried in an atmospheric environment, and the battery-grade graphite-activated carbon 
composite material is obtained. The preparation method has the advantages of being simple in process, rich in raw materials, short in manufacturing cycle and low in 
energy consumption and has good 
economic benefits, environmental benefits and 
social benefits.