With　its　layered　structure,　abundant　functional　groups,　and　excellent　electrical　conductivity,　MXene　is　of　great　research　interest　in　the　field　of　gas　sensing.　The　preparation　technology　of　gas　sensors　is　constantly　being　optimized,　opening　up　avenues　for　the　development　of　gas　sensing.　MXene-based　composite　materials　(MXene/graphene,　MXene/metal　oxides,　MXene/MOF,　and　MXene/polymer)　are　applied　in　various　gas　sensors.　With　the　development　of　science　and　technology,　the　scale　of　industrial　production　continues　to　grow,　and　the　types　and　quantities　of　gas　raw　materials　used　in　industrial　production　and　produced　during　the　production　process　are　also　constantly　increasing.　These　gases　include　flammable　and　explosive　gases,　and　even　contain　toxic　gases.　Therefore,　it　is　very　important　and　necessary　for　gas　sensors　to　detect　and　monitor　these　gases　quickly　and　accurately.　In　recent　years,　a　new　two-dimensional　material　called　MXene　has　attracted　widespread　attention　in　various　applications.　Their　abundant　surface　functional　groups　and　sites,　excellent　current　conductivity,　tunable　surface　chemistry,　and　outstanding　stability　make　them　promising　for　gas　sensor　applications.　Since　the　birth　of　MXene　materials,　researchers　have　utilized　the　efficient　and　convenient　solution　etching　preparation,　high　flexibility,　and　easily　functionalize　MXene　with　other　materials　to　prepare　composites　for　gas　sensing.　This　has　opened　a　new　chapter　in　high-performance　gas　sensing　materials　and　provided　a　new　approach　for　advanced　sensor　research.　However,　previous　reviews　on　MXene-based　composite　materials　in　gas　sensing　only　focused　on　the　performance　of　gas　sensing,　without　systematically　explaining　the　gas　sensing　mechanisms　generated　by　different　gases,　as　well　as　summarizing　and　predicting　the　advantages　and　disadvantages　of　MXene-based　composite　materials.　This　article　reviews　the　latest　progress　in　the　application　of　MXene-based　composite　materials　in　gas　sensing.　Firstly,　a　brief　summary　was　given　of　the　commonly　used　methods　for　preparing　gas　sensing　device　structures,　followed　by　an　introduction　to　the　key　attributes　of　MXene　related　to　gas　sensing　performance.　This　article　focuses　on　the　performance　of　MXene-based　composite　materials　used　for　gas　sensing,　such　as　MXene/graphene,　MXene/Metal　oxide,　MXene/Transition　metal　sulfides　(TMDs),　MXene/Metal-organic　framework　(MOF),　MXene/Polymer.　It　summarizes　the　advantages　and　disadvantages　of　MXene　composite　materials　with　different　composites　and　discusses　the　possible　gas　sensing　mechanisms　of　MXene-based　composite　materials　for　different　gases.　Finally,　future　directions　and　inroads　of　MXenes-based　composites　in　gas　sensing　are　presented　and　discussed.