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FME-SPH coupling method was applied to simulate the mechanism of rock fragmentation by TBM cutters. The 3D coupling models of rock fragmentation by single TBM cutter and two TBM cutters were established. The mechanism of rock fragmentation by TBM cutters was analyzed. The conclusions are summarized as follows: for the rock fragmentation by single TBM cutter，in the stage of the formation of the crused zone，beneath the thrust of a single cutter，microcracks extend downward to form a fan-shaped failure zone；beneath the tangential force of a single cutter，microcracks propagate forward to form the other fan-shaped failure zone. The two fan-shaped failure zones consist of a conical failure zone in rock. In the stage of the formation of microcracks，the growth rate of radial crack is faster than that of median crack. In the stage of the propagation of microcracks，the growth rate of median crack is faster than that of radial crack. When the cutter scrolls to the edge of rock，the fan-shaped failure occurs on the edge of rock. for the rock fragmentation by two TBM cutters，in the initial stage，each cutter independently acts on the rock. A conical failure zone is first formed beneath each cutter. In the stage of the formation of microcracks，the propagation direction of the Hertzian cracks between two cutters are changed because of the interaction of two cutters. In the stage of the propagation of microcracks，Hertzian cracks between the two cutters coalesce，then the rock chipping is formed. [ABSTRACT FROM AUTHOR]