Research Center for Wire Rod, Xingtai 054027, Hebei, China)The composition, size and dispersion of macro- inclusions on the failure fracture surface of 1950MPa- grade inductive tempering spring wire obtained from Nakamura rotating bending test and spring fatigue test were analyzed by SEM- EDS. The composition, size and dispersion of micro- inclusions in spring steel wire rod 55SiCrA were analyzed by ASPEX Explorer automated scanning electron microscope. According to the results of comparison, the compositions of macro- inclusions on the fracture surface and micro- inclusions in spring steel wire rod are almost identical, which manifest that the macro- inclusions come from deoxidization and emulsified slag. Based on the characteristics of size and dispersion of macro- inclusions on the failure fracture surface, it is assumed that the critical size of inclusion is 20μm under this fatigue test condition. Finally, it is pointed out that the application of an inclusion plasticity control technique and the optimization of the mold flow field to improve the bloom subsurface cleanliness are the further improvement directions.