Supercritical　CO2　(sCO2)　Brayton　cycle　usually　shows　high　efficiency　and　also　has　compact　structure,　which　can　be　considered　as　a　promising　alternative　in　future　coal-fired　power　plants.　However,　sCO2　boiler　has　different　structures　and　configurations　compared　with　the　conventional　steam　boiler,　especially　for　the　arrangement　of　radiative　heat　transfer　surfaces.　Proper　design　of　vertical　gas　wall　and　reheat　gas　wall　is　crucial　to　the　success　design　of　sCO2　boiler.　In　this　study,　a　thermohydrodynamic　model　of　radiative　heat　transfer　surfaces　was　developed　to　predict　pressure　drops　and　wall　temperature　distributions.　A　sCO2　power　cycle　calculation　model　was　employed　to　comprehensively　analyze　the　influences　of　pressure　drops　on　the　thermal　efficiency.　A　300　MW　sCO2　boiler　was　taken　into　account　as　the　baseline　case　and　thermohydrodynamic　analyses　of　gas　wall　and　reheat　gas　wall　were　carried　out.　The　influences　of　flow　directions　and　mass　fluxes　on　wall　temperature,　pressure　drops　and　thermal　efficiency　were　obtained　by　the　present　models.　Then,　optimized　structures　of　radiative　heat　transfer　surfaces　were　proposed,　i.e.,　vertical　downward　gas　wall　with　tubes　of　φ34　×　4　mm　and　vertical　upward　reheat　gas　wall　with　tubes　of　φ57　×　6　mm.　Accordingly,　the　net　cycle　efficiency　achieved　an　optimized　value　of　50.07%　under　the　conditions　that　the　wall　temperatures　of　radiative　heat　transfer　surfaces　did　not　exceed　the　allowable　temperature.　©　2020　Elsevier　Ltd