Abstract: In order to improve the mechanical properties of sulphur free cutting steel,a new type of sulphur free cutting steel was designed and prepared.Optical microscopy,SEM,EDS and tension test machine were used to investigate the composition segregation,microstructure,sulphide and mechanical properties.The results show that carbon,sulphur and manganese had a plus segregation in the billet especially the columnar zone,and the as-rolled microstructure was composed of ferrite and pearlite.The main sulphide was MnS with sphericity,and it was elongated,broken up and dispersed in the matrix after rolled.Compared to SAE 1118 steel,the strength of the developed steel was improved to 590 MPa,and the hardness to 160-176 HB,it could meet the performance requirements of engine screw.