Abstract: According to the characteristic of nuclear grade ZrB₂-IFBA burnable poison, the nuclear ZrB₂ ultrafine powders were prepared by sol-gel technology and thermal carbon reduction process, using boric acid and zirconium nitrate as the source of B and Zr and glucose as the source of C. The phase composition, micro morphology, and element content by mass of the samples were analyzed by X-ray diffraction, field emission scanning electron microscope, and chemical titration. The results show that, the ultrafine ZrB₂ powders in the average particle diameter of 0.41 μm can be obtained when Zr: B: C=1:2.2:6.5 by mole at 1300℃ as heat preservation for 2 h. Compared with the existing industrialization preparation process of ZrB₂ powder, the B loss rate reduces significantly, and the minimum loss rate of B is 10.6% by mass in the whole process.