The invention provides a preparation method of FTO/CuO nanowires. The preparation method includes the steps of: 1) cleaning and air-drying conductive glass; 2) dissolving PVP in deionized water, stirring the solution until clarification, successively adding urea and sodium tartrate, adding copper sulfate and stirring the mixture to obtain a mixed solution, and moving the mixed solution and the conductive glass into a polytetrafluoroethylene reaction lining, performing a reaction at 120 DEG C for 24 h, cooling the reaction product to room temperature, and washing and drying the reaction product to obtain a solid thin film sample; 3) calcining the solid thin film sample at 550 DEG C for 3 h to obtain the FTO/CuO nanowires. The invention also provides the FTO/CuO nanowires prepared through the method and applications of the FTO/CuO nanowires. The method successfully prepares the CuO nanowires, wherein surface area and carrier concentration of the CuO nanowires are increased and morphologic consistency of the material before and after annealing treatment is maintained. The material can be used for photocatalytic water splitting to produce hydrogen.