In order to deeply understand the ice crystal icing(ICI)phenomenon in aero-engines,grasp the characteristics of ICI process,and establish scientific and effective ICI protection means,literature and data onICI in recent years were investigated and summarized. The discovery and confirmed processes of ICI were re-viewed. The differences between ICI and supercooled water icing,simulation tests and computational methods ofICI were emphasized. At last,several directions for the further research on the ICI proble...