Abstract: This study addresses the issues of severe wear and low rock-breaking efficiency of shaft sinking by drilling methods in the Jurassic strata of Western China, focusing on milled-tooth roller cutter commonly used in this drilling method. The contact behavior between the milled-tooth roller cutter and the rock is elucidated, and the rock-breaking modes of single-ring, single-row cutter teeth are analyzed. The calculation formulas for vertical force and rolling force are derived, and a rock-breaking force calculation model for a three-tooth milled-tooth roller cutter is established. Using numerical simulations, the critical penetration that defines the rock-breaking mode is determined, and the validity of the rock-breaking force calculation model is verified through rotary rock-breaking experiments. Finally, the influence of key factors such as penetration, cutter rotational speed and tool body parameters on the rock-breaking force is discussed. The main findings are as follows. The rock-breaking mode of the single-ring cutter tooth of the milled-tooth roller cutter can be divided into progressive rock breaking and non-progressive rock breaking, while the rock-breaking mode of the single-row cutter tooth can be classified into cutter tooth cooperative rock breaking and non-cooperative rock breaking. When h≥5.33 mm, the front and rear rows of teeth exhibit progressive rock breaking. When h≥3.06mm, the teeth within the same row exhibit coordinated rock breaking. Both vertical force and rolling force show a positive correlation with penetration, cutter's rotational speeds, and cutter tooth edge length. Reducing the row spacing and tooth spacing can decrease the critical penetration for progressive rock breaking and cooperative rock breaking. The research results provide valuable reference for the design optimization of rock-breaking tools for shaft sinking by drilling methods of Jurassic strata in Western China and for studies on mechanical rock-breaking mechanisms under similar conditions.