The invention provides a flexible self-driven broadband spectrum photoelectric detector and a preparation method thereof, and belongs to the technical field of a photoelectric detector. The photoelectric detector comprises two parts A and B, wherein the A part comprises a carbon fiber, an electron transfer layer and a perovskite light absorbing layer which are formed on the surface of the carbon fiber successively; the B part comprises a copper wire, an electron blocking layer and a copper oxide layer which are sequentially formed on the surface of the copper wire; and the A part and the B part are twisted to form a twisted-pair wire structure, so as to enable the perovskite light absorbing layer to contact the copper oxide layer. The flexible self-driven broadband spectrum photoelectric detector can still work normally under the condition of no external energy supply, realizes self-driving of the detector, and can realize broadband spectrum detection of ultraviolet-infrared (350 nm to1050 nm), wherein the detection spectral range can replace a traditional silicon-based photoelectric detector, thus effectively broadening the application range of the perovskite-based photoelectricdetector.