Aninversemethodispresentedforestimatingtheunknownboundaryincidentradiationheatfluxononesideofone-dimensionalsemitransparentplanarslabwithsemitransparentboundariesfromtheknowledgeoftheradiationintensitiesexitingfromtheotherside.Theinverseproblemissolvedusingconjugategradientmethodofminimizationbasedondiscreteordinatesmethod(DOM)ofradiativetransferequation.TheequationsofsensitivitycoefficientsarederivedandeasilysolvedbyDOM,withtheresultthatthecomplicatednumericaldifferentiationcommonlyusedinsolvingsensitivitycoefficientsisavoided.Theeffectsofanisotropicscattering,absorptioncoefficient,scatteringcoefficient,boundaryreflectivity,fluidtemperatureoutsidetheboundaries,convectionheattransfercoefficients,conductioncoefficientofsemitransparentmediaandslabthicknessontheaccuracyoftheinverseanalysisareinvestigated.Theresultsshowthattheboundaryincidentradiationheatfluxcanbeestimatedaccurately,evenwithnoisydata.