Corrosion　is　a　common　problem　in　offshore　oil　and　gas　wells,　especially　in　thermal　recovery　wells,　and　will　greatly　affect　the　residual　strength　of　casing　strings.　Field　data　show　that　the　corrosion　pattern　of　casing　is　mainly　pitting,　local　corrosion　and　uniform　corrosion,　of　which　pitting　is　the　most　common.　For　this　reason,　based　on　the　engineering　practice　of　thermal　recovery　well　casing　corrosion,　the　dynamic　changes　of　wellbore　temperature　and　pressure　during　the　gas　production　process　of　thermal　recovery　wells　are　considered,　and　the　numerical　model　of　casing　corrosion　under　transient　temperature　and　pressure　coupling　was　established.　The　influence　of　corrosion　morphology　and　corrosion　depth　on　the　residual　strength　of　the　casing　was　analyzed,　and　the　transient　stress　variation　law　of　the　corroded　casing　was　studied.　The　results　show　that:　(1)　under　the　same　corrosion　depth,　both　pitting　and　uniform　corrosion　will　reduce　the　residual　internal　pressure　and　external　extrusion　strength　of　the　casing　string,　and　the　degree　of　influence　is　similar.　The　effect　of　uniform　corrosion　on　the　residual　tensile　strength　of　the　casing　string　was　larger　than　pitting　and　local　corrosion.　(2)　The　residual　strength　of　the　casing　decreased　linearly　with　the　increase　of　the　corrosion　depth　of　the　casing.　(3)　The　stress　of　the　corrosion　part　of　the　casing　showed　a　significant　dynamic　change,　in　the　initial　stage　of　steam　injection,　casing　stress　rised　rapidly　at　the　corrosion　position,　and　then　the　rate　at　which　the　casing　stress　rises　was　slowed,　which　tends　to　cause　fatigue　damage　to　the　casing.　The　research　results　have　the　reference　significance　for　the　assessment　of　the　service　status　of　offshore　thermal　recovery　well　casings.　©　2019　Trans　Tech　Publications,　Switzerland.