The invention discloses a method for preparing a TbMnO3 heterogeneous junction with a photoelectric characteristic. In the method, a TbMnO3 film with the thickness of 100 to 150nm epitaxially grows on an n-type conductive niobium strontium titanate (Nb-SrTiO3) substrate with the thickness of 0.5mm, and a TbMnO3/Nb-SrTiO3 heterogeneous junction is formed at an interface between the film and the substrate. The method comprises the following five steps of: 1, sintering a TbMnO3 target material at a high temperature by a solid-phase reaction method; 2, preparing the film by a pulse laser deposition method; 3, arranging the TbMnO3 film in a double-beam system for gallium ion implantation; 4, characterizing a microstructure of the film by using an X-ray diffraction instrument, and analyzing an epitaxial growth direction of the film; and 5, sputtering platinum serving as an upper electrode and the substrate serving as a lower electrode on the film, and measuring and optically modulating voltage and current characteristics by using a tester. The method is scientific in conception and advanced in processes, and has practical value and a wide application prospect in the technical field of electronic technology engineering.