Abstract: The reasons for elongation disqualification for the steel used for motorcycle frame were studied by means of tensile testing and optical microscopy, scanning electron microscopy and energy diffraction. The results show that the main reasons for elongation disqualification for the steel used for motorcycle frame were serious layering in tensile fracture, a large number of nonmetal oxide and silicon calcium acid salt inclusions existing in tensile fracture, as well as the layering and inclusions coexistence. The slab center segregation could be effectively eliminated and the level of inclusions could be reduced by optimizing the steelmaking process. Increasing the rolling compression ratio could reduce or prevent fracture layering. Some measures, including high temperature heating at 1 180-1 250 ℃, high temperature rolling at over 1 100 ℃ and high temperature finish rolling at 870-870 ℃ as well as low temperature coiling at 610-640 ℃, could improve microstructure and mechanical properties of the steel used for motorcycle frame, and made its elongation meet related requirements.