Abstract: High temperature ductility test for 1.2% Si cold-rolled non-oriented electrical steel slab at 600~1 300 ℃ has been carried out by Gleeble1500 stress/strain thermomechanical simulator.Thermoplasticity and intensity curve of samples under testing temperatures was obtained,then through the observation of inclusions in the brittleness area and the fracture surface of samples at different temperatures,the mechanism of the brittle fracture in its brittleness temperature zone was analyzed.The results show that there exist a brittleness temperature zone Ⅰ at above 1 220 ℃ and a low-plasticity temperature zone between 600 ℃ and 780 ℃ in 1.2% Si cold-rolled non-oriented electrical steel slab at strain rate of 1.0×10^-3s^-1 and test temperature of 600~1 300 ℃.One reason for the decrease of plasticity of 1.2% Si cold-rolled non-oriented electrical steel at the temperature between 600 ℃ and 780 ℃ is that it is very difficult to recrystallize,and another is the existence of AlN from ferrite in low temperature zone and crystal embitterment due to the precipitation of aluminosilicate.