Chemically Assisted Dry Comminution (CADC) of sericite powder, a kind of mica, was conducted in order to prepare ultra-fine sericite with minimal contamination from the grinding media. CADC of sericite powder is a comminution method in which the sericite powder is first mixed with another powder, ＇＇powder B＇＇, and the mixed powder is comminuted in dry conditions, followed by obtaining fine sericite after removing the powder B by use of a simple method such as dissolution. ＇＇Assisted＇＇ means that powder B assists comminuting the sericite by some interaction with the sericite during the comminution. Various nitrates such as LiNO3, NaNO3, KNO3 and RbNO3 were used as powder B. Compared with the results of ordinary dry comminution, sericite powder with a larger specific surface area and fewer impurities from the grinding media, was prepared by CADC. The specific surface area of sericite obtained by CADC has a correlation with the decrease of potassium ion in sericite. Potassium ion was thought to be exchanged during the comminution.