Confining　pressure　is　an　important　factor　that　affects　the　rock　breakage　efficiency　of　Tunnel　Boring　Machines　(TBMs).　This　study　analyses　the　influence　of　the　confining　pressure　on　the　rock　breakage　process,　rock　breakage　efficiency　and　fragmentation　distribution　after　crushing　using　a　coupled　FEM-DEM　method.　First,　the　parameters　of　the　rock　numerical　model　are　calibrated　using　numerical　uniaxial　compression　tests　and　Brazilian　tests.　Second,　the　rock　breakage　by　the　cutter　is　simulated　under　different　confining　pressures,　and　the　influence　of　the　confining　pressure　on　the　rock　breakage　process　is　determined.　Third,　using　a　post-processing　program　developed　for　extracting　the　induced　fragments,　the　distribution　of　fragments　after　rock　fragmentation　is　obtained,　which　accurately　provides　the　fractured　area　of　the　rock　to　determine　the　variation　of　the　specific　energy　(SE)　with　confining　pressure.　Finally,　the　equivalent　length　distributions　of　the　fragments　are　analysed　using　the　fractal　method.　The　results　show　that　the　confining　pressure　has　a　significant　inhibitory　effect　on　the　propagation　of　median　cracks.　The　angle　of　the　lateral　crack　increases　with　increasing　confining　pressure,　and　the　length　of　the　crack　first　increases　and　then　decreases.　The　maximum　normal　force　and　the　maximum　indentation　distance　also　increase　first　and　then　decrease　with　increasing　confining　pressure.　The　SE　first　increases　with　increasing　confining　pressure;　however,　when　the　confining　pressure　reaches　the　first　critical　value,　the　SE　begins　to　decrease　with　increasing　confining　pressure　and　then　continues　to　increase　after　the　confining　pressure　reaches　the　second　critical　value.　The　variation　of　the　fractal　dimension　with　the　confining　pressure　is　similar　to　the　variation　of　the　SE　with　the　confining　pressure.