Kerfing　on　the　working　face　of　tunnel　boring　machine　(TBM)　can　reduce　the　integrity　of　intact　rock　mass,　it＇s　one　of　feasible　methods　to　improve　the　TBM　performance.　When　the　TBM　cutter　cut　along　the　midline　of　two　kerfs,　the　chipping　mechanism　changed　to　the　interaction　between　the　cutter　and　adjacent　kerfs,　the　lateral　cracks　generated　from　the　cutter　tip　could　propagate　to　the　bottom　of　adjacent　kerfs.　To　study　the　effects　of　kerf　depth　on　the　cracks　pattern　and　the　cutting　performance　of　the　TBM　cutter,　a　series　of　full-scale　linear　rock　cutting　tests　were　conducted.　In　addition,　conventional　cutting　tests　without　kerfs　were　also　performed　to　make　a　comparison.　The　cutter　force　and　rock　muck　were　collected,　and　the　rock　samples　were　sectioned　after　the　tests.　The　cracks　patterns　beneath　the　cutter　tip　were　observed　by　fluorescent　dye.　The　results　show　that　the　dip　angle　of　the　lateral　cracks　increase　with　the　increasing　kerf　depth,　the　vertical　cracks　become　shorter　and　less.　Besides,　the　area　of　the　crushed　zone　decreases.　The　required　normal　force　and　rolling　force　are　much　reduced　even　for　the　large　cutter　penetration　compared　with　the　conventional　cutting.　The　cutter　forces　decrease,　while　the　charac-teristic　grain　diameter　and　coarseness　index　of　the　rock　muck　increase　with　the　increasing　kerf　depth.　The　specific　energy　of　kerf-assisted　cutting　is　lower　than　that　of　the　conventional　cutting,　and　it　declines　as　the　kerf　depth　increases.　A　critical　kerf　spacing　to　depth　ratio　is　found　to　efficiently　reduce　the　specific　energy.　The　results　are　useful　for　the　rational　parameter　design　of　the　kerfing　system　installed　on　the　new　generation　TBM.　The　kerf　spacing　could　be　enlarged　to　save　energy　if　the　kerfs　are　deeper　than　12　mm.　However,　it＇s　still　a　challenging　task　to　create　deep　kerfs　on　site.