Natural　gas　hydrate　has　become　a　hotspot　for　researchers　because　of　its　considerable　economic　benefits　and　potential　strategic　significance.　In　the　hydrate　exploitation　process,　the　hydrate-bearing　sediments　get　damaged,　and　the　coupling　effect　of　multi-physical　fields　is　involved.　In　this　study,　a　damage　constitutive　model　of　hydratebearing　sediments　is　established　by　considering　decomposition　damage,　loading　damage,　and　the　influence　of　residual　strength.　Based　on　this　damage　constitutive　model,　a　Thermo-Hydro-Chemo-Mechanical　(THCM)　multifield　coupling　model　considering　the　sediment　damage　is　constructed　on　the　COMSOL　simulation　platform.　Compared　with　the　experimental　data,　the　THCM　coupling　model　is　demonstrated　and　employed　to　study　the　depressurization　process　of　horizontal　wells　in　permafrost　regions.　During　the　hydrate　exploitation　model,　changes　in　displacement,　saturation,　average　pore　pressure,　and　temperature　at　different　mining　positions　are　recorded　and　analyzed.　The　results　indicate　that　the　damaging　of　sediments　has　a　significant　effect　on　soil　deformation　and　temperature.　After　the　sediment　damaging　effect　is　considered,　the　minimum　temperature　of　the　extraction　points　is　reduced　by　22.5%　at　most.　The　maximum　deformation　of　the　extraction　points　is　about　11.8%　greater　than　that　without　considering　the　sediment　damage　effect.　Moreover,　the　model　reveals　the　selfpreservation　effect　of　gas　hydrate.　The　temperature　of　the　surrounding　soil　at　the　exploitation　site　decreases　due　to　hydrate　decomposition,　which　would　inversely　promote　hydrate　formation.　These　numerical　models　in　this　study　can　be　applied　to　estimate　the　strength　of　sediments　and　predict　the　reservoir　settlement　in　the　process　of　hydrate　depressurization.