For the thin-film thermo-electric generator and fabrication method of this invention, a P-type thermo-electric thin-film layer, an insulating thin-film layer and a N-type thermo-electric thin-film layer is deposited on a substrate to form a three-layer PN junction, multiple three-layer PN junctions in series are available, an insulating thin-film layer is provided between every to serial three-layer PN junctions, and electrodes are extracted from the substrate and the outermost thin-film layer of the last three-layer thin-film PN junctions. The present invention applies the deposition of P-type thermo-electric thin-film layer, an insulating thin-film layer and a N-type thereto-electric thin-film layer to form a three-layer PN junction, thus a thermo-electric generator is formed, during the deposition of the insulating thin-film layer, intentionally sheltering the substrate and one end of the deposited thin-film layer and depositing the P-type or N-type materials on the substrate and one end of the deposited thin-film layer directly, to form a connection of PN junction or a serial connection between two PN junction, the separate connection of the P-type or N-type materials is not required, simplifying the fabrication processes of the thin-film thermo-electric generator, owning to the function of the thin-film thermo-electric materials and serial connection structure of multiple three-layer PN junctions, the performance of the thin-film thermo-electric generator is greatly improved.