Nose-to-nose　technology　is　a　new　method　for　calibrating　the　broadband　sampling　oscilloscope,　and　the　data　acquired　by　it　is　kick-out　pulse　response　waveform.　But　transition　duration　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　transition　duration　of　broadband　sampling　oscilloscope　based　on　nose-to-nose　technology　is　proposed.　The　main　uncertainty　factors　from　nose-to-nose　technology　is　analyzed　and　formulas　calculating　uncertainty　are　given.　Then　the　algorithm　about　propagation　of　uncertainty　is　deduced　according　to　the　process　of　data　processing.　The　estimation　about　uncertainty　of　transition　duration　of　broadband　sampling　oscilloscope　is　given　finally.