Abstract: Cr12MoV cold work die steel with different tellurium content was prepared by non-vacuum smelting, and the hardness was modulated to 60 HRC. The tellurium modification rule on inclusions in test steel was studied. The effect of tellurium on the processing performance was quantitatively evaluated by milling and drilling tests and surface roughness measurement. The results show that by tellurium modification, MnS-(Cr,Mn) Te complex inclusions of MnS coated with (Cr, Mn) Te and (Cr, Mn) Te inclusion could be formed in the test steel. With the increase of tellurium content, the number and size of inclusions increased and their shape tended to be spherical. With the increase of tellurium content, the milling force, drilling force and surface roughness after milling of the test steel decreased, indicating that the processing performance and surface machining quality were improved.