Joint　spacing　is　one　of　the　most　important　geological　factors　which　affect　TBM　performance.　In　this　work,　the　full-scale　cutting　tests　on　the　granite　rock　samples　with　two　sets　of　joint　spacing　(100　mm　and　400　mm)　respectively　were　conducted　by　using　the　mechanical　rock　fragmentation　experimental　platform　of　Beijing　University　of　Technology.　In　these　tests,　the　diameter　of　the　disc　cutter　with　a　constant　cross　section　(CCS)　is　17　inches　(432　mm).　The　size　of　tested　sample　is　1000　mm×1000　mm×600　mm,　taken　from　Beishan,　Gansu　province　of　China.　During　the　tests,　the　three-dimensional　forces　acting　on　the　rolling　cutter　were　recorded,　and　the　rock　chips　collected　after　each　cutting　pass　were　weighed　individually.　The　impact　of　joint　spacing　on　rock　fragmentation　process　by　TBM　cutter　was　investigated　by　analyzing　the　obtained　cutting　force,　crack　propagation　modes　and　rock　chips.　The　results　show　that　for　the　rock　mass　with　joint　spacing　100　mm,　the　normal　force　required　to　indent　into　the　rock　is　less　than　that　of　intact　rock.　For　the　rock　mass　with　joint　spacing　400　mm　the　normal　force　required　have　a　process　of　mutation,　For　the　rock　mass　with　joint　spacing　100　mm,　two　fragmentation　modes　are　found　during　TBM　cutter　cutting.　While　for　the　rock　mass　with　joint　spacing　400　mm,　the　fragmentation　process　can　be　divided　into　normal　fragmentation　and　joint-affected　fragmentation　process,　and　the　median　crack　can　be　promoted　to　propagate　vertically　to　joint　plane.　The　rock　sample　under　joint　plane　is　intact,　joint　plane　can　limit　the　crack　propagating　cross　the　joint　plane.　©,　2015,　Editorial　Office　of　China　Civil　Engineering　Journal.　All　right　reserved.