This　study　focused　on　the　mechanical　properties　of　the　ethylene　tetrafluoroethylene　(ETFE)　membrane　at　temperatures　between　-20　and　140　degrees　C,　the　thermal　expansion　performance　from　the　ambient　temperature　of　25　degrees　C　to　140　degrees　C,　and　the　thermal　deformation　performance　from　the　ambient　temperature　of　25　degrees　C　to　80　degrees　C.　According　to　the　experimental　study,　the　mechanical　properties,　the　glass　transition　temperature,　the　coefficient　of　thermal　expansion　(CTE),　and　the　thermal　deformation　strain　model　of　ETFE　at　different　temperatures　were　obtained.　Finally,　the　thermal　deformation　mechanism　is　proposed,　namely　that　the　thermal　deformation　strain　is　equal　to　the　thermal　expansion　strain　and　elastoplastic　strain　produced　by　the　change　of　the　strain-stress　relationship.