Abstract: The content and microstructure of scale of Kanthal Super 1700 MoSi2 heating element were studied using scanning electron microscope (SEM) with energy dispersive spectrometer (EDS).A homogeneous and smooth glass scale more than 10 μm in thickness was observed.The interface between scale and matrix was very clear and excellent bond was formed.This scale was composite glass with high content SiO2 and less oxides of Al,Na,Mg and Ca.A layer of Mo5Si3 with 1-2 μm in thickness was observed between glass scale and matrix.That composite glass scale and Mo5Si3 substrate would be beneficial to adjust the difference of coefficient of thermal expansion between scale and matrix.They can also improve the bonding stability of scale and matrix.This is good for the application of MoSi2 heating element.