Nose-to-nose　technology　is　a　new　method　for　calibrating　broadband　sampling　oscilloscope,　and　the　data　acquired　is　a　kick-out　pulse　response　waveform.　But　the　bandwidth　of　broadband　sampling　oscilloscope　is　a　quantity　calculated　from　kick-out　pulse　response　waveform　by　a　series　of　arithmetic,　e.g.　deconvolution.　A　full　estimating　method　about　uncertainty　of　bandwidth　of　broadband　sampling　oscilloscope　based　on　nose-to-nose　technology　is　proposed.　First,　the　main　uncertainty　factors　from　nose-to-nose　technology　is　analyzed.　Then　the　flow　of　propagation　algorithm　is　proposed　according　to　the　process　of　data　processing　which　calculated　bandwidth　from　measured　and　the　propagation　algorithm　based　on　linear　interpolation　is　deduced.　Finally　the　estimation　is　given　about　uncertainty　of　transition　duration　of　bandwidth　sampling　oscilloscope.