A self-powered automobile exhaust gas sensor including a supporting frame, a ferroelectric-triboelectric coupling functional film, and two metal electrodes. The ferroelectric-triboelectric coupling functional film comprises a first end fixed on the supporting beam in middle of the supporting frame, and a second end is freestanding. The two metal electrodes are grounded and adhered on the upper and lower sides of the supporting frame, respectively. An iron block is mounted on the top of the supporting frame. The ferroelectric-triboelectric coupling functional film includes a negative triboelectric charging layer, a ferroelectric composite material layer and a positive triboelectric charging layer; the ferroelectric composite material layer is prepared via casting method by mixing the ferroelectric material and the gas-sensitive material; the negative triboelectric charging layer has stronger electron affinity ability than the positive triboelectric charging layer, and attracts electrons from the positive triboelectric charging layer.