The　geological　environments　of　ultra　deep　wells　such　as　high　temperature　and　high　pressure　(HTHP),　narrow　safety　density　window　pose　significant　challenges　to　cementing　operation.　Considering　segmental　rheological　model　and　density　model,　casing　eccentricity,　U-tube　effect　and　viscous　dissipation,　this　paper　established　a　transient　temperature　and　pressure　coupling　model　during　cementing　injection　stage　of　ultra　deep　wells.　The　segmental　rheological　model　can　describe　the　rheological　properties　of　cementing　fluids　under　HTHP　much　better.　Considering　casing　eccentricity　and　viscous　dissipation　can　accurately　model　the　variation　of　temperature　and　pressure　profiles.　Taking　U-tube　effect　into　the　model,　the　formation　process　of　vacuum　section　at　top　of　the　casing　can　be　simulated.　The　fully　implicit　finite-difference　approach　was　used　to　solve　the　coupling　model,　and　the　calculation　results　were　compared　with　field　measurement　data　and　simulation　data　to　verify　its　accuracy.　The　calculation　errors　of　the　developed　model　are　respectively　10%　and　5%　compared　to　field　measurement　data　and　Wellplan＇s　simulation　data.　Numerical　simulations　were　conducted　to　reveal　the　cementing　fluid　distribution,　transient　temperature　distribution　and　pressure　distribution　during　the　cementing　injection　stage.　The　simulation　results　show　that　the　variety　of　cementing　fluids　with　different　density,　rheological　properties　and　thermophysical　parameters　complicates　the　change　mechanism　of　temperature　and　pressure.　The　temperature　and　pressure　distributions　both　present　unsteady　characteristics　during　cementing　injection　stage,　which　puts　forward　higher　requirements　of　pressure　control　for　narrow　safety　density　window　formation.　The　influence　of　temperature　and　pressure　on　rheology　of　cementing　fluids　cannot　be　ignored,　and　segmental　rheological　model　should　be　considered　for　accurate　pressure　prediction.　Also　the　casing　eccentricity　cannot　be　ignored　for　cementing　pressure　calculation　in　deviated　or　horizontal　wells.　Managed　pressure　cementing　(MPC)　has　a　greater　advantage　in　dealing　with　narrow　density　window　formation.　The　synergistic　control　of　cementing　fluid　density　and　back　pressure　can　keep　the　equivalent　circulating　density　(ECD)　within　the　safe　density　window.　Through　the　application　of　the　transient　temperature　and　pressure　coupling　model,　we　can　simulate　the　variations　of　key　dynamic　parameters　during　cementing　injection　stage　and　optimize　the　cementing　parameters.