With　the　continuous　advancement　of　electronic　devices,　flexible　thin　films　with　both　thermal　management　functions　and　excellent　electromagnetic　interference　(EMI)　shielding　properties　have　received　much　attention.　Hence,　inspired　by　Janus,　a　CNF/MXene/ZnFe2O4@PANI　composite　film　with　an　asymmetric　gradient　alternating　structure　was　successfully　prepared　by　adjusting　the　filler　content　of　the　conductive　and　magnetic　layers　using　a　vacuum-assisted　filtration　method.　Benefiting　from　the　magnetic　resonance　and　hysteresis　loss　of　ZnFe2O4@PANI,　conductive　loss　and　dipole　polarization　of　MXene,　as　well　as　the　exclusive　“absorption-reflection-reabsorption”　shielding　feature　in　the　alternating　multilayered　films,　CM&CZFP-4　G　film　has　superior　EMI　shielding　performance,　with　an　EMI　SE　of　up　to　45.75　dB　and　shielding　effectiveness　of　99.99　%.　Surprisingly,　the　composite　film　maintains　reliable　EMI　shielding　properties　even　after　prolonged　erosion　in　harsh　environments　such　as　high/low　temperatures,　high　humidity,　acids　and　alkalis.　Furthermore,　the　CM&CZFP-4　G　responded　quickly　within　about　50　s　and　reached　a　maximum　steady-state　temperature　of　235.8　°C　at　an　applied　voltage　of　9.0　V,　indicating　the　obtained　film　acquired　outstanding　and　controllable　Joule　heating　performance.　This　result　was　attributed　to　the　homogeneous　dispersion　of　MXene　to　build　up　a　conductive　network　and　endow　the　CNF/MXene　with　high　conductivity.　Meanwhile,　the　fire　resistance　of　CM&CZFP-4　G　was　significantly　improved　compared　to　pure　CNF,　which　guaranteed　fire　safety　during　its　application.　Additionally,　contributed　by　long　fiber　entanglement　of　CNF,　extensive　hydrogen-bonding　interactions　and　multilayer　structural　design,　the　CM&CZFP-4　G　film　exhibits　excellent　mechanical　characteristics,　with　the　tensile　strength　and　fracture　strain　of　27.74　MPa　and　6.21　%,　separately.　This　work　offers　a　creative　avenue　to　prepare　multifunctional　composite　films　with　electromagnetic　shielding　and　Joule　heating　for　various　application　environments.　©　2024