The invention provides a preparation method of a graphene heat conducting film and belongs to the technical field of graphene materials. The problems that according to the conventional preparation method of the graphene heat conducting film, the technology is complicated and obtained graphene is low in orientation degree, poor in heat conducting property and low in tensile strength are solved. The method comprises: first soaking graphite in an acid-blended solution, and then adding an intercalator and stirring the mixture so as to obtain a mixed solution; then, adding an organic reagent into the mixed solution for reaction so as to obtain graphene aqueous dispersion; adding natural plant macrofibers or polymer macrofibers into the graphene aqueous dispersion, and carrying out ultrasonic processing so as to obtain fiber and graphene mixed dispersion; and finally arranging the fiber and graphene mixed dispersion on a substrate, and processing a film obtained after drying at a temperature of 500-900 DEG C for 15-30 minutes so as to obtain the graphene heat conducting film. The graphene heat conducting film prepared by the method has high orientation degree. The heat conducting coefficient can reach 1000-1500W/mK, and the mechanical tensile strength can reach 30-70MPa.