Ionic　liquids　(ILs)　have　been　applied　as　an　environmentally　friendly　solvent　in　the　pretreatment　of　lignocellulosic　biomass　for　more　than　a　decade.　The　ILs　involved　pretreatment　processes　for　cellulases　mediated　saccharification　lead　to　both　the　breakdown　of　cellulose　crystallinity　and　the　decrease　of　lignin　content,　thereby　improving　the　solubility　of　cellulose　and　the　accessibility　of　cellulase.　However,　most　cellulases　are　partially　or　completely　inactivated　in　the　presence　of　even　low　amount　of　ILs.　Immobilized　cellulases　are　found　to　perform　improved　stability　and　higher　apparent　activity　in　practical　application　compared　with　its　free　counterparts.　Enzyme　immobilization　therefore　has　become　a　promising　way　to　relieve　the　deactivation　of　cellulase　in　ILs.　Various　immobilization　carriers　and　methods　have　been　developed　and　achieved　satisfactory　results　in　improving　the　stability,　activity,　and　recycling　of　cellulases　in　IL　pretreatment　systems.　This　review　aims　to　provide　detailed　introduction　of　immobilization　methods　and　carrier　materials　of　cellulase,　including　natural　polysaccharides,　synthetic　polymers,　inorganic　materials,　magnetic　materials,　and　newly　developed　composite　materials,　and　illustrate　key　methodologies　in　improving　the　performance　of　cellulase　in　the　presence　of　ILs.　Especially,　novel　materials　and　concepts　from　the　recently　representative　researches　are　focused　and　discussed　comprehensively,　and　future　trends　in　immobilization　of　cellulases　in　non-natural　ILs　environments　are　speculated　in　the　end.　©　2019,　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.