The　risetime,　bandwidth　and　their　relative　conversion　factors　are　important　qualification　of　all　types　of　oscilloscopes.　By　applying　the　theory　of　linear　network　to　studying　the　oscilloscopes,　the　methods　ascertaining　the　conversion　factors　are　generalized,　summarized　and　enriched,　and　the　changing　principle　of　the　conversion　factor　is　revealed.　The　conversion　factor　between　the　risetime　and　bandwidth　for　broadband　sampling　oscilloscope　are　studied.　The　conclusion　shows　that　the　conversion　factor　of　a　real　product　is　related　to　several　factors　which　are　the　module　type　of　signal　channel,　the　serial　number　of　production,　the　mode　of　bandwidth　and　the　setting　of　channel,　etc.　For　the　broadband　sampling　oscilloscope　of　Angilent　86100　series,　the　conversion　factors　distribute　approximately　among　the　range　of　0.35-0.47.