The invention provides a method of preparing high-purity niobium wire for nuclear fuels with a general industrial niobium bar as a raw material. The method comprises the following steps: 1, carrying out electron beam melting on the general industrial niobium bar to obtain an ingot; 2, turning processing; 3, extruding to obtain an extruded bar billet; 4, after turning processing, carrying out first-stage annealing treatment; 5, rotating forging to obtain a rotating forged bar billet; 6, carrying out second-stage annealing treatment, and then carrying out surface sanding to obtain a sanded bar billet; 7, drawing a roller die to obtain a rough wire billet; 8, after surface treatment, carrying out fixed die drawing and shaping to obtain a half finished wire product; and 9, after surface treatment, carrying out straightening to obtain the high-purity niobium for the nuclear fuels with the diameter being 1.5-3.0mm and the straightness being smaller than 3mm/m. The method is less in thermal treatment fire times, little in thermal processing and high in rate of finished product. According to the high-purity niobium wire prepared by the invention, the size, surface inspection and components of the high-purity niobium wire all accord with the requirement on a nuclear material, and the high-purity niobium wire can be directly used for preparing uranium-niobium alloy for the nuclear fuels.