Abstract: High temperature mechanical property of oriented silicon steel with main inhibitor Cu₂S produced by the thin slab casting and rolling was tested, comparing reduction of area and SEM of fracture surface in 600~1 300 ℃ and analyzing effects of C (0.020%~0.044%), Cu (0.18%~0.49%) and Mn (0.06%~0.16%) on hot ductility of oriented silicon steels.The results showed that hot ductility trough moved to lower temperature and higher ductility with the content of C, Cu and Mn increasing;hot ductility was improved because C and Mn enlarge γ phase;Cu can also enlarge γ phase, and then decrease of grain-boundary strength of the steel became lower and ductility was improved, because that S and Cu created Cu₂S, and Cu₂S makes fluid phase which make against hot ductility and sulfide including iron reduce, so Cu improve hot ductility.