The invention discloses a preparation method for an expanded graphite filter material. The preparation method comprises the following steps: mixing graphite flakes, concentrated sulfuric acid and potassium dichromate, carrying out heating in a water bath at 40 to 50 DEG C, then carrying out filtering and drying so as to obtain expanded graphite M, placing the expanded graphite M into a chloride solution, and carrying out heating expansion so as to obtain expanded graphite N; and mixing the expanded graphite N, aluminum silicate fiber, glycerol stearate and glycol, and carrying out dry-press molding so as to obtain the expanded graphite filter material. The filter material prepared by using the method provided by the invention has the advantages of excellent adsorbability, high porosity and strong oil-adsorbing capacity.