Abstract: In order to reduce the internal quality problems of high-strength steel bars billets produced by HBIS Cheng Steel，the single factor method was used to analyze the effects of molten steel superheat，casting speed, secondary cooling intensity and whether the mould powder is baked on the central segregation, center porosity, corner crack and intermediate crack of billets by macrostructure analysis and statistics of casting billets. The results show that the superheat of molten steel is controlled within the range of 16-25 ℃，the casting speed is 1.70 m/min，and the secondary cooling intensity is 1.0 L/kg and under the condition of baking mould powder, the internal quality of the billets can be effectively improved.

Key words: casting billets, macrostructure analysis, internal quality