Near-stoichiometric ZrB2 nanofibers are synthesized via carbothermal reduction using electrospinning technique. Polyzirconoxane (PZO), boric acid and polyacrylonitrile (PAN) are used as zirconia, boron and carbon sources, respectively. ZrB2 is obtained by pyrolyzing the as-spun green fibers at 1500 C for an hour in argon or vacuum. The obtained ZrB2 nanofibers are composed of uniformly nano-sized single crystals. The products are rather pure, containing only zirconium, boron and a small amount of oxygen. The atomic percentages of zirconium and boron in the nanofibers formed in vacuum at 1500 C are 33.4% and 62.8% respectively, which is very close to the stoichiometric ratio of ZrB2. The nanofibers are characterized by XRD, SEM, EDS, TEM and TG-DTA.