The invention discloses a preparation method for a lightning-protection semiconductor material, belonging to the technical field of lightning-protection semiconductor materials. The preparation method provided by the invention comprises the following steps: weighing ball-milled flake graphite powder, adding the ball-milled flake graphite powder into a reaction solution of potassium dichromate and sulfuric acid so as to obtain a reactant, soaking the reactant with sodium nitrate, after the completion of soaking, carrying out calcination so as to obtain a calcined substance, mixing the calcined substance with ferric sulfate and ferric chloride, adding alkali and carrying out a reaction so as to generate ferroferric oxide, carrying out ultrasonic dispersion and crystallization so as to obtain modified expanded graphite, mixing the modified expanded graphite with polyaniline and the like, and carrying out granulation so as to obtain the lightning-protection semiconductor material. According to the invention, the flake graphite powder is used as a raw material, and the surface of the flake graphite powder is modified and loaded with nanometer ferroferric oxide, so excellent performances like electric conduction, lubrication and shapability can be achieved; charges accumulated on the surface of the semiconductor material can be remotely migrated at a constant speed; the disadvantage of imbalance of local current and ionic current on the surface of a traditional semiconductor material can be compensated; and instance results prove that the lightning-protection semiconductor material provided by the invention has the advantages of good adhesiveness with a composite material, excellent lightning-protection effect and wide economic prospects.