Abstarct: Mechanized excavation method has some advantages such as decreasing vibration, decreasing manpower, increasing the advance speed and other points compared to the conventional methods. Therefore, use of TBM has increased to construct underground spaces Because of the major need for underground spaces. Unlike traditional methods, the use of TBM requires a lot of preliminary studies. Due to the importance of the time and cost of project, the prediction of the TBM performance is an important part of these studies. The TBM performance is influenced by various factors such as geomechanical and operational factors. Geomechanical factors include intact rock and discontinuities characterization. Also, the operational factors include the torque and thrust, the geometry of the discs, the distance between the discs and the way they are placed on the cutterhead. So far, many studies including analytical, empirical and numerical modeling have been done to investigate the effect of these factors on the penetration rate of TBM. The TBM performance is basically dependent on the performance of the cutting disc because of the cutting tools is intermediate element of the transfer of energy (Thrust and torque) from the cutterhead to the rock and finally leads to crushing. Linear cutting test is one of the most popular laboratory methods which is known as an accurate and reliable method for evaluating the cutting disc performance and its effective parameters. The high cost of sample preparation in this method and the cost of carrying out the test, as well as the unusually of this test, to investigate the effect of cross-cutting on the cutting in the rocks is due to the limitations of this method. Therefore, numerical models have been developed to compensate for these limitations. Nowadays, the distinct element numerical method of is a common method for analyzing discontinuous environments and processes such as crushing stone by cutting tools. In this research, for modelling the effect of discontinuities geometric characterization on the cutting performance has been done using particle flow code (PFC3D) software due to the ability to simulate crack growth as well as degradation modeling under the influence of stress variation. At the First, by simulating a granite sample and creating multiple slices with a disc cutter with a diameter of 43 cm in distance and the depth of the various penetrations on it, the amount of force applied to the disk and the effect Two parameters of distance and depth of influence on these forces have been investigated and finally the results have been compared with the results of laboratory research in this field. The results of this section of the research show a good agreement between modeling and laboratory results. At the end, the effect of discontinuous with different geometric properties on the performance of the cutting disc has been investigated. The results of the cross-section analysis show that the effect of the discontinuities on cutting performance decreases with increasing spacing between the discontinuities. Also, by examining the joint directional parameter, it is indicated that when the discontinuities have an angle of 60 degrees relative to the front, the best cutting performance is obtained. It should be noted that, however, this result is true for interchanges greater than parts 10 cm.