A　novel　vegetable　cutting　mechanism　is　designed　and　fabricated,　which　is　capable　of　measuring　cutting　force　and　blade　displacement　in　real　time.　Rhizome　tissue　of　lettuce　is　selected　as　cutting　object　of　vegetable　cutting　mechanism.　And　a　series　of　experiments　were　carried　out　with　the　vegetable　cutting　mechanism　under　drawing　force.　The　drawing　force　has　contribution　to　separating　rhizome　tissue　of　lettuce　from　soil　slightly,　which　will　facilitate　the　process　of　cutting　rhizome　tissue　of　lettuce　by　vegetable　cutting　mechanism.　Cutting　speed,　cutting　method,　blade　parameters,　and　so　on　can＇t　affect　the　process　phase　of　cutting.　However,　larger　cutting　speed　can　reduce　sampling　size　of　cutting　force,　resulting　in　the　distortion　of　the　relation　curve　of　cutting　force　and　cutting　depth.　So,　experimental　conditions　are　the　cutting　speed　of　50　mm/min,　the　drawing　force　of　30　N,　the　cutting　position　of　10　mm　above　stem　of　lettuce,　and　the　cutting　method　of　cutting　vertically.　Blade　parameters　are　blade　width　of　0.5　mm,　wedge　angle　of　blade　of　20°,　and　material　of　cast　iron.　According　to　the　experimental　results,　the　cutting　process　can　be　divided　into　3　phases:　Deformation　phase,　rupture　phase　and　cutting　phase.　The　process　that　blade　cuts　into　rhizome　tissue　of　lettuce　is　defined　as　deformation　phase.　In　the　deformation　phase,　the　work　done　by　blade　is　converting　the　elastic　energy　stored　in　the　rhizome　tissue　of　lettuce.　The　epidermal　fiber　structure　of　rhizome　tissue　is　changed　under　pressure　of　blade.　Therefore,　it＇s　difficult　to　establish　a　physical　model　and　an　analytical　model　for　deformation　phase.　However,　the　cutting　force　of　deformation　phase　is　represented　as　a　typical　nonlinear　J　shape　curve,　so　an　exponential　function　is　used　to　fit　it　in　this　paper.　Once　the　blade　breaks　into　the　surface　of　the　rhizome　tissue,　the　cutting　force　suddenly　decreases　while　crack　is　created,　which　is　defined　as　rupture　phase.　The　time　of　rupture　phase　is　very　short,　so　there　is　almost　no　energy　conversion　between　the　blade　and　the　vegetable.　Only　elastic　energy　stored　in　the　deformation　phase　is　released　instantaneously.　The　cutting　force　shows　a　huge　decrement　in　a　short　time,　so　the　cutting　force　is　simplified　as　a　linear　decrement.　Consequently,　the　blade　cuts　into　internal　fibrous　tissue,　and　the　cutting　force　firstly　increases　and　then　decreases　with　the　increment　of　cutting　depth,　which　is　defined　as　cutting　phase.　In　the　cutting　phase,　the　elastic　energy　stored　in　the　deformation　phase　changes　very　little,　and　the　elastic　energy　produced　by　drawing　force　is　converted　into　the　energy　consumed　by　the　newly　formed　surface.　The　mathematical　model　of　cutting　force　is　established　according　to　the　energy　balance　theory　in　this　phase.　The　test　cutting　force　value　is　considered　as　benchmark.　The　error　in　deformation　stage　is　-5.3%-7.8%,　and　the　error　in　cutting　phase　is　-9.6%-8.2%.　The　cutting　force　curves　of　experiment　and　the　mathematical　model　are　well　matched,　so　the　correctness　of　modeling　of　cutting　process　is　proved.　Research　results　show　that　the　cutting　force　reaches　the　maximum　critical　value　in　deformation　phase;　the　drawing　force　has　a　certain　effect　on　decreasing　the　cutting　force,　but　excessive　drawing　force　is　easy　to　cause　uneven　cutting　surface　and　poor　harvest　effect.　The　results　can　help　researchers　to　understand　cutting　characteristics　and　cutting　mechanism　of　soft　tissue　of　vegetable,　and　it　provides　a　possible　solution　for　improving　vegetable　cutting　devices　in　the　future.　In　addition,　although　this　paper　is　aimed　at　mathematical　modeling　of　the　cutting　process　of　the　rhizome　tissue,　the　analysis　and　modeling　methods　of　the　cutting　process　are　also　suitable　for　other　soft　tissue　materials.　©　2017,　Editorial　Department　of　the　Transactions　of　the　Chinese　Society　of　Agricultural　Engineering.　All　right　reserved.