The invention relates to a perovskite photoelectric detector based on a composite electron transport layer. The perovskite photoelectric detector structurally comprises a substrate, a conductive anode, a hole transport layer, a perovskite photoactive layer, a composite electron transport layer, a hole barrier layer and a metal cathode from bottom to top sequentially, wherein the composite electrontransport layer is formed by a mixture of PCBM and gelatin; and the composite electron transport layer comprises 0.1%-6% by mass of gelatin and the balance PCBM. With the adoption of the composite electron transport layer doped with a bioactive material, namely, gelatin, the surface topography of an original PCBM electron transport layer is improved, so that an original mesoporous interface becomes uniform and compact, the device has better water oxygen resistance and anti-ultraviolet capability, the stability of the perovskite photoelectric detector is improved, and the working life is prolonged; besides, the carrier transport capability of the electron transport layer is improved, leakage current in work of devices is reduced, dark current is substantially reduced, and finally, the detection performance of the perovskite photoelectric detector is improved.