The invention discloses a preparation method of a bend-resistant flexible photoelectric device. In an alcohol phase system, zinc salt is used as a reaction source, metal salt is used as a doping source, a highly-conductive metal-doped zinc oxide precursor solution is prepared under low temperature condition, finally the bend resistance of a prepared metal-doped zinc oxide film is improved by adding a polymer or micromolecular organic matter solution having functional groups, the conductivity of the metal-doped zinc oxide film is 1.68*10<-3> S/m, the light transmittance thereof is greater than90%, the metal-doped zinc oxide film is applied to a photoelectric device as a cathode interface layer, and the efficiency can be maintained above 80% after being bent for 100 times. The preparation temperature of the metal-doped zinc oxide solution does not exceed 80 DEG C, the preparation process is simple, the preparation method is energy saving and environmental friendly, and the product stability is good. The nano material prepared by adopting the preparation method has the advantages of good bending resistance, good adhesion and high electrical conductivity, therefore the nano material has good application prospect in the field of photoelectric devices such as large-area flexible solar cells.