In　this　paper,　the　integrated　emissivity　of　isothermal　cylindrical　cavity　is　calculated　based　on　ANSYS　finite　element　method　at　different　wall　material　emissivity　and　Cavity　length,　and　are　compared　with　the　calculation　results　of　the　Monte　Carlo　method,　the　average　absolute　deviation　is　0.00045.　Meanwhile,　this　paper　presents　meshing　rules　of　the　cavity　bottom　surface　and　the　cavity　mouth　surface,　it　proposes　that　the　cavity　mouth　surface　is　regarded　as　the　equivalent　radiant　surface,　and　calculates　the　integrated　emissivity　of　different　positions　on　the　equivalent　radiant　surface,　analyzes　the　influence　of　the　wall　material　emissivity,　cavity　length,　the　position　of　radius　direction.　©　(2012)　Trans　Tech　Publications,　Switzerland.