Abstract: The rock-breaking mechanism of TBM disc cutter is a crux in the study and application of TBM. From the disc cutter indenting test, the linear grooving test and circular grooving test of TBM, it is found that the rock-breaking styles of TBM are different, so is the spalling of rock. Based upon the above tests, aiming at the interaction between the arc-edged domain and rock, this paper develops the calculation theory and method to calculate the displacement and strain of rock at points neighboring the arc edge of disc cutter. The disc cutter interacts with rocks in different fashions, and it has mainly 3 working manners: existing cutting depth, gradually reaching required depth and linear grooving of disc cutter. This study establishes a solid foundation for research on rock-breaking mechanism of disc cutter.