The　operating　conditions　of　municipal　solid　waste　incineration　(MSWI)　are　influenced　by　manipulated　variables,　such　as　the　feed　rate,　primary　air,　and　grate　speed,　as　well　as　non-manipulated　variables,　such　as　municipal　solid　waste　(MSW)　particle　size,　mixing　coefficient,　emissivity,　moisture　content,　and　the　ratio　of　C　to　O.　Based　on　the　actual　data　of　an　MSWI　plant　in　Beijing,　a　non-manipulated　variable　single-factor　analysis　of　solid-phase　combustion　in　the　furnace　was　carried　out　based　on　the　biorthogonal　numerical　simulation　experiment.　First,　a　solid-phase　combustion　analysis　of　the　MSWI　process　was　performed　for　non-manipulated　variables,　with　the　main　non-manipulated　variables　determined.　Then,　based　on　FLIC　2.3c　software,　the　numerical　model　was　established　under　benchmark　operating　conditions.　Based　on　the　biorthogonal　experiment,　several　groups　of　numerical　model　inputs　were　designed　to　generate　mechanism　data　in　multi-operating　conditions.　Finally,　a　multi-condition　numerical　simulation　experiment　was　used　to　study　solid-phase　combustion　under　different　conditions　and　analyze　non-manipulated　variables.　The　simulation　results　showed　that　the　maximum　solid　temperature　was　1360　K　under　the　benchmark　operating　condition　and　ranged　from　1120　to　1470　K　under　five　conditions.　Large-size　particles　and　large　emissivity　were　beneficial　to　solid-phase　combustion,　while　high　moisture　content　and　a　large　mixing　coefficient　weakened　combustion.　The　results　provide　support　for　the　subsequent　optimal　control　of　the　whole　MSWI　process.　©　2023　by　the　authors.