Disclosed is a method of fabricating a graphite sheet, including: polymerizing diamines and a dianhydride to form a polyamic acid. The polyamic acid is solvent casted on a substrate and hot baked to form a polyamic acid film or gel film. The polyamic acid film or gel film is biaxially stretched at a high temperature imidization or chemical imidization to form the polyimide film. The polyimide film is then carbonized and graphitized to form a graphite sheet. The diamines include a diamine of Formula 1 and a diamine of Formula 2, and the dianhydride includes a dianhydride of Formulae 3, Formula 4, Formula 5, Formula 6, Formula 7, Formula 8, Formula 9, or combinations thereof.