Abstract: In order to investigate the characteristics of muscovite powder ultrafine grinding process, SEM、XRD、XPS and FTIR were used to character ultrafine grinding product muscovite, and the results show that the drifting of binding energy of K was bigger when ultrafine grinding time less than 0.5 h, which indicates that muscovite ruptures mainly along the direction of its cleavage plane; However, when ultrafine grinding time more than 0.5 h, the drifting of binding energy of K was bigger, indicating that muscovite mainly breaks along the direction being parallel to its end face when ultrafine grinding time more than 1 h; As increasing of gringding time, the morphology of muscovite changed from flake with irregular edge to granular, and the particle was obviously refined. The strengths of characteristic XRD diffraction peaks of muscovite gradually decrease. Additionally, the asymmetrical stretching vibration peaks of Si-O bond degenerate and broaden, but symmetric stretching vibration absorption peaks split. It is believed that the ordered structure of muscovite powder was gradually destroyed, then the amorphous transformation occured in the process of gringding. This study may serve as a reference for optimization of ultrafine grinding process parameters and industrial production of muscovite.