The invention relates to an epoxy primer for electrostatic spraying of a rail traffic bogie, and a preparation method thereof. Epoxy resin, a composite antirust material, a coloring pigment, a functional material slurry, an assistant and a solvent form a paint; low-molecular polyamide, alicyclic amine, an assistant and a solvent form a curing agent; and the primer is prepared from the paint and the curing agent according to a weight ratio of 100:20 when constructed, and a proper amount of a diluent is added to adjust the construction viscosity in order to facilitate construction. The epoxy primer can adapt to mixed gas electrostatic spray gun spraying and electrostatic adsorption, and has the advantages of good environmental protection effect, small paint mist spray, high painting rate, good conductivity in a dry film, no influences on the electrostatic spraying, and realization of a coating layer with the performances meeting technical requirements of the primer for rail traffic bogie, and the epoxy primer can reduce the use amount of a paint by 30% or more when used in the mixed gas spray gun electrostatic spraying construction of the rail traffic bogie in order to reduce paint mist and the emission of VOCs, so the epoxy primer is an environmentally-friendly coating.