Understanding　the　phase-transition　processes　of　van　der　Waals　(vdW)　materials　plays　a　vital　role　in　their　performance　control　and　application　development.　Here,　we　investigate　the　structural　transitions　and　Raman　identifications　of　the　monoclinic　and　orthorhombic　phases　of　the　layered　vdW　magnet　CrI2.　At　present,　the　characterization　of　these　two　phases　remains　a　challenge,　and　our　first-principles　calculations　show　that　they　each　have　a　specific　Raman　spectrum,　which　proposes　a　reliable　method　to　identify　them.　Moreover,　we　discover　that　CrI2　with　orthorhombic　phase　exhibits　both　ferroelectricity　and　magnetism　simultaneously　due　to　its　unique　interlayer　stacking　order,　indicating　that　it　will　provide　a　platform　for　the　popular　sliding　ferroelectricity　and　multiferroicity.