With　the　development　of　tunnel　construction,　the　inserted-tooth　roller　cutter　has　been　widely　used　for　many　types　of　excavation　machines,　including　tunnel　boring　machines,　raised　drills,　roadheaders,　etc.　Thus,　it　is　significant　to　study　the　rock　fragmentation　mechanism　and　efficiency　under　the　inserted-tooth　roller　cutter　for　improving　mechanical　excavation　efficiency.　For　this　issue,　rotary　cutting　tests　for　the　inserted-tooth　roller　cutter　with　diameter　of　12　inches　were　conducted　using　the　mechanical　rock　fragmentation　platform　of　Beijing　University　of　Technology.　The　rock　sample　used　in　the　rotary　cutting　test　was　Beishan　granite　with　dimensions　1000　mm　×　1000　mm　×　600　mm.　A　series　of　rotary　cutting　tests　for　the　different　rows　of　teeth　and　the　whole　cutter　were　conducted　under　different　penetration　depths.　During　the　rotary　cutting　tests,　the　cutting　force,　rock　chips,　and　rock　fragmentation　efficiency　were　measured　collected　and　analyzed.　Moreover,　the　distribution　characteristics　of　cracks　induced　by　the　cutters　were　explored　by　fluorescence　experiment　to　verify　the　rock　fragmentation　mechanism.　The　main　conclusions　can　be　summarized　as　follows.　The　mode　of　rock　fragmentation　by　inserted-tooth　roller　cutter　in　a　＇progressive＇　way,　in　which　rock　breakage　propagated　from　the　adjacent　single　spherical　tooth　with　small　spacing　to　adjacent　rows　of　teeth　with　large　spacing;　For　the　tests　on　different　rows　of　teeth,　the　rock　fragmentation　efficiency　of　the　third　row　is　the　highest.　For　the　test　of　the　whole　cutter,　the　rock　fragmentation　is　highest　with　penetration　depth　of　1.5　mm;　Based　on　the　results　of　the　fluorescence　experiment,　the　distribution　characteristics　of　the　cracks　induced　by　the　cutter　were　identified,　and　there　are　obvious　differences　in　the　propagation　direction　and　range　of　cracks　under　each　row　of　teeth.　The　rock　fragmentation　efficiency　obtained　from　crack　distribution　coincided　with　the　analysis　of　cutter　force　and　rock　chips.　The　conclusions　of　this　study　can　offer　some　guidance　for　the　optimization　of　cutter　layout,　cutter　type,　and　operating　parameters　of　excavation　machines.　©　2018,　Editorial　Department　of　China　Journal　of　Highway　and　Transport.　All　right　reserved.