Abstract: The HRB500E high-strength aseismic steel bars produced by a company were displayed brittle fracture during the cold bending test. The chemical compositions, microstructure, fracture morphology and inclusion compositions of the brittle fractured steel bar were examined and analyzed by direct reading spectrometer, optical microscope, scanning electron microscope and energy dispersive spectrometer, respectively. The results show that a large number of ultra-long and ultra-wide silicate inclusions caused by molten steel oxidation were the main reason for the cold bending brittle fracture of the HRB500E high-strength aseismic steel bars.