The invention discloses a method for preparing isotropic graphite containing coal-based needle coke as aggregate. The method comprises the following steps of: firstly, thoroughly mixing binders and aggregates at a weight ratio of (0.2 to 0.6):1 in the form of kneading under the condition of being higher than the softening point of the binder; performing cold isostatic pressing on the mixture and then charring to obtain a biscuit-firing product under such conditions that the cold isostatic pressing pressure is 100 to 200 Mpa and the charring temperature is 800 DEG C to 1000 DEG C; putting the product in a container, feeding an impregnant (i.e. asphalt), evacuating the impregnation system until the pressure is below 500 Pa, introducing molten asphalt, impregnating under 0.5 to 1.5 Mpa and maintaining for 1 hour, and calcining at 500 DEG C to 1000 DEG C; and putting the resulting product in a graphitizing furnace, performing graphitizing treatment at 2200 DEG C to 3000 DEG C and maintaining for 0.5 to 1 hour. The method has the advantages of easily-accessible raw material, high yield and low cost; and the product is advantageous in high graphitization degree, low volatile component and ash contents, high compression strength and good isotropic indexes.