Abstract: The component fluctuation of 20CrMnTiH steel in Laiwu Special Steel Plant was large,the-hardenability bands belt was HRC 8-10,this constrained the further improvement of gear steel quality.Based on the research,it was found that center segregation especially carbon segregation in blooms was the major prob-lem.By taking measures,especially the increase of electromagnetic stirring,the center carbon segregation was markedly improved;C control between 0.19%~0.22% reached 95.6%;hardenability bands belt control in HRC 6 reached 92.1% and in HRC 4 reached 86.2%.The quality of products is improved and the needs of users are met.