A better understanding of the hard-brittle material removal mechanism in wire-sawing provides a basis for optimizing the wire-saw and processing parameters. The maximum cutting depth of each diamond grain in wire-sawing is given. It is proved theoretically that the deformation mode on the machined hard-brittle material surface gradually shifts from brittle fracture to ductile deformation with the increasing of wire-saw velocity, the decreasing of infeed velocity and the decreasing of average grain size. The experimental investigation on the wire-sawing of granite is carried out. It is shown that in the case of wire-saw velocity of 20m/s, infeed velocity of 0.15mm/s and diamond grain size of 200~230#, the removal mechanism in wire-sawing is ductile mode.