Polyester-based,　self-adhesive　asphalt　waterproofing　membranes　have　garnered　significant　attention　due　to　their　extensive　use　in　building-waterproofing　projects,　with　their　resistance　to　aging　in　complex　environments　being　particularly　crucial.　This　study　evaluates　the　performance　changes　of　these　membranes　under　thermo-oxidative　aging　and　freeze-thaw　cycling　conditions.　The　thermo-oxidative　aging　process　was　simulated　using　a　thin-film　oven　and　combined　with　freeze-thaw　cycle　tests　to　assess　membrane　performance　at　various　aging　stages.　Changes　in　functional　groups　were　analyzed　via　Fourier　Transform　Infrared　Spectroscopy　(FTIR),　and　tests　for　low-temperature　flexibility,　tensile　properties,　and　peel　strength　were　conducted.　The　results　demonstrated　that　aging　significantly　reduced　the　membrane＇s　low-temperature　flexibility　and　peel　strength,　accompanied　by　oxidative　reactions　and　a　loss　of　lightweight　components.　This　study　provides　essential　data　on　the　aging　behavior　of　the　membrane　and　offers　a　theoretical　foundation　for　its　long-term　application　in　practical　engineering.