With　the　advancement　of　oil　and　gas　exploration　at　home　and　abroad　in　the　direction　of　deep-sea,　deep　and　unconventional　resources,　it　is　increasingly　difficult　to　calculate　the　wellbore　pressure　accurately　during　the　drilling　process.　Moreover,　a　large　number　of　studies　have　shown　that　the　traditional　rheological　models　such　as　Bingham　model　and　power-law　model　are　not　very　consistent　with　the　actual　rheology　of　drilling　fluid　in　the　wellbore.　Besides,　temperature　and　pressure　have　a　great　influence　on　the　rheology　of　drilling　fluid.　Therefore,　it　is　important　to　select　the　optimal　rheological　model　at　different　temperatures　and　pressures　to　describe　the　rheology　of　drilling　fluid　for　accurate　calculation　of　wellbore　pressure.　In　this　study,　FannIX77　high　temperature　and　high　pressure　automatic　rheometer　is　used　to　carry　out　rheology　test　experiments　of　water-based　and　oil-based　drilling　fluids.　It　is　found　that　the　rheology　of　drilling　fluid　is　greatly　affected　by　temperature　and　pressure,　and　the　influence　of　temperature　is　more　significant.　Using　the　1st　OPT　software　and　regression　fitting　algorithm,　it　is　found　that　the　rheology　of　water-based　drilling　fluid　is　more　in　line　with　the　Herschel-Bulkley　model　when　the　temperature　is　less　than　100 °C,　and　more　in　line　with　the　four-parameter　model　when　the　temperature　is　greater　than　100 °C.　The　rheology　of　oil-based　drilling　fluid　is　more　in　line　with　the　Herschel-Bulkley　model　when　the　temperature　is　less　than　140 °C,　and　more　in　line　with　the　four-parameter　model　when　the　temperature　is　greater　than　140 °C.　Therefore,　this　study　establishes　a　wellbore　temperature　and　pressure　field　model　considering　the　segmented　rheological　model.　Then,　this　study　uses　example　well　data　to　compare　with　the　calculation　results　of　wellbore　friction　pressure　drop　of　the　model　and　under　wellbore　temperature　and　pressure　field　model　with　different　rheological　models.　It　is　found　that　the　calculation　results　of　the　wellbore　temperature　and　pressure　field　model　considering　the　segmented　rheological　model　are　more　consistent　with　the　actual　data　in　the　field.　This　study　provides　theoretical　guidance　for　accurate　calculation　of　wellbore　pressure.　©　2024,　The　Author(s),　under　exclusive　license　to　Springer　Nature　Switzerland　AG.