The invention provides a plasmon FET based on a gold-copper oxide nanowire network structure and a preparation method. The method comprises the steps that a cuprous oxide nanowire is prepared; a surfactant and a weak reducing agent are dissolved in distilled water and heated, and a constant temperature is maintained; the cuprous oxide nanowire is poured into the solution and stirred to acquire a mixed solution; the pH value of a chloroauric acid solution is adjusted to alkalescence; the chloroauric acid solution is slowly added into the mixed solution to form an Au-Cu2O nanocomposite structure; the Au-Cu2O nanocomposite structure is dissolved in a solvent mixture with water and a small surface tension to acquire an Au-Cu2O nanocomposite structure solution; the Au-Cu2O nanocomposite structure solution is uniformly deposited on an FET substrate to form a nanowire network structure, and the nanowire network structure is naturally dried at a low temperature; and low temperature thermal annealing is carried out to ensure that the nanocomposite structure ohmically contacts a gold wire on the substrate to form the FET with the Au-Cu2O nanowire network structure. The manufacturing method provided by the invention has the characteristics of simplicity, rapidity and low cost. The plasmon FET is more sensitive than a conventional FET, and the detection range of the plasmon FET is wider than the detection range of the conventional FET.