When　tunnel　boring　machines　(TBMs)　excavate　intact　high-strength　rock　masses,　creating　kerfs　on　the　tunnel　face　is　a　promising　solution　to　enhance　the　efficiency　of　TBM　cutters.　The　cutters　can　be　arranged　to　cut　between　kerfs　or　cut　along　kerfs.　The　rock　breaking　mechanism　of　cutting　along　kerfs　is　not　fully　revealed　yet,　and　a　quantified　comparison　in　cutting　performance　between　the　two　arrangements　is　needed.　This　study　investigated　the　rock　breaking　mode　and　efficiency　of　cutting　along　kerfs　by　linear　cutting　tests.　Different　combinations　of　kerf　depth　(D)　and　cutter　penetration　(P)　were　designed.　Cutter　force,　vibration,　muck　characteristics　and　rock　breaking　specific　energy　were　analyzed.　The　results　revealed　two　distinct　modes　existed　in　cutting　along　kerfs.　Grooving　mode　occurred　when　P　was　2　mm　or　when　D　was　twice　P,　the　kerf　facilitated　the　formation　of　a　thick　crushed　zone　while　constrained　the　expansion　of　lateral　cracks,　the　kerfs　were　enlarged　into　grooves,　producing　much　rock　powder,　the　cutter　force　and　vibration　were　significantly　reduced　compared　to　cutting　without　kerfs.　Chipping　mode　occurred　when　D　was　not　greater　than　P,　macro　cracks　accumulated　and　extended　to　the　bottom　of　the　adjacent　kerf　after　multiple　layers　of　cuts,　producing　large　rock　chips,　although　the　cutter　force　and　vibration　were　higher　than　those　of　the　grooving　mode,　the　specific　energy　was　significantly　lower.　The　performance　parameters　of　cutting　along　kerfs　were　compared　with　those　of　cutting　between　kerfs　from　another　research.　The　rock　formation　in　the　chipping　mode　was　less　efficient　than　cutting　between　kerfs,　while　the　cutter　force　and　vibration　in　the　grooving　mode　were　significantly　lower.　Consequently,　a　conceptual　cutterhead　design　for　kerf-assisted　cutting　was　proposed,　which　combined　the　advantages　of　the　two　cutting　arrangements.　The　study　contributes　to　the　development　of　a　new　generation　of　kerf-assisted　TBMs.