Abstract: We followed the production of 20CrMnTi and 42CrMo steel and took the samples of cast bloom and rolled bar at the same batch.By analyzing their macrostructure and carbon macrosegregation,we found the carbon segregation had definitely inherit characteristics from cast bloom to its rolled bar,which led to segregation with ingot shape in the rolled bar,and the macrostructure of rolled bar was related with solidification structure of cast bloom.We observed the segregation in the rolled bar under the optical microscope and found that the rolled bar had different macrostructure in and out of the ingot-shape area.We also found banded structure in the 20CrMnTi steel which was bad for homogeneity and finally influenced the quality of finished products.