Jitter　is　one　of　the　important　factors　that　affect　the　measurement　accuracy　of　broadband　sampling　oscilloscopes.　The　description　of　jitter　varies　across　different　fields,　and　therefore,　the　definition　and　classification　of　jitter　differ　among　international　organizations.　This　paper　analyzes　the　sources　and　definitions　of　jitter　involved　in　the　time-domain　measurements　of　broadband　sampling　oscilloscopes　and　characterizes　jitter　using　Root-Mean-Square　Jitter　(jitter　rms)　and　Peak-to-Peak　Jitter　∗(jitter　p-p)　for　a　more　rigorous　and　accurate　representation.　Additionally,　this　paper　conducts　research　using　Keysight　Flex　DCA　simulation　software　as　a　platform　and　provides　the　calculation　methods　for　jitter　rms　and　jitter　p-p　in　the　Keysight　NIOOO　series　broadband　sampling　oscilloscopes.　©　2023　IEEE.