Abstract: The dissolution behavior of alumina in molten cryolite was investigated by using a transparent quartz crucible, where the dissolution process was recorded by a video camera. The influencing factors of dissolution velocity of alumina were analyzed and discussed. The results show that there are two stages in dissolution process, i.e., the rapid dissolution and the peeling-off dissolution of alumina crusted with electrolyte. The alumina dissolves at different velocities in molten cryolite because when feeding the alumina into the crucible, the temperature of electrolyte decreases so as to form alumina/electrolyte agglomerate on the surface of electrolyte to reduce the contact area between alumina and cryolite. The dissolution velocity of alumina rates to the stirring rate, preheating temperature of alumina, melt temperature and the kinds of alumina used.