Abstract: TTT curve was constructed using SHTT II melting and crystallization temperature measuring instrument,then the mold flux devitrification activation energy was calculated at different levels of CaF₂.To calculate the rate of crystallization and analysis crystalline phase,X-ray diddractometer combining with the JADE software are utilized.Various surface morphology of slag film protection with different CaF₂ content under the different temperature treatment was observed under the metallographic microscope,exploring the impact of CaF₂ on the devitrification of slag.It is found out that the temperature and activation energy of initial devitrified phenomenon decreases and the roughness on the surface of flux film increases with the CaF₂ content increasing.The mineral species tend to be single with treating temperature of glassy flux film increasing.