Due to the harsh tunnelling environment, it is difficult to carry out realtime force monitoring of tunnel boring machine (TBM) disc cutter. Hence, the characteristics of disc cutter components and the transferring law of load are analyzed, a strain gauge is embedded in cshaped cushion block, an effective monitoring method is proposed, and effectiveness and feasibility of the monitoring method are proved by the calibration test of the cshaped support block and the rotary rockbreaking test. The test results show that: (1) Under the condition of different penetration degrees, the vertical load obtained by the stress monitoring method is slightly different from that of the oil cylinder, and the variation trends of the stresses are almost the same, which indicates the feasibility and effectiveness of the monitoring method. (2) With the increase of penetration degree, the normal and lateral forces of the disc cutters increase.