To reveal the dynamic excavation performance of full-face hard rock tunnel boring machine (TBM) disc cutter group under free faces, laboratory excavation experiments were carried out on a concrete sample by a group of full-scale disc cutters assisted by a pilot hole, and numerical excavation simulations were conducted on a rock specimen by a group of full-scale disc cutters under the assistance of pre-cut kerfs. The characteristics and performances of the free-face-assisted rock excavation of the multi-stage-cutterhead TBM and the waterjet-assisted TBM were analyzed and evaluated. For the specimen with uniaxial compressive strength of approximately 40 MPa, the structure of the free face of the pilot hole follows a periodic evolution pattern of “vertical?inclined?horizontal?vertical”, and the affected area is concentrated in 2?4 disc cutters near the free face. The critical spacing and height of the free face are 180 and 130 mm, respectively. The total excavation thrust is reduced by 10% to 20%, and the boreability of the surrounding rock is improved by 6.7% to 21.0%. Under the condition of concentric-ring type pre-cut kerfs, the rock-breaking load first decreases and then stabilizes with increasing kerf depth, and the rock-breaking efficiency first increases and then stabilizes with increasing kerf depth. The critical value of pre-cut kerf depth is 40 mm, the excavation thrust decreases by a minimum of 36%, and the excavation efficiency increases by a minimum of 56%, compared with the simulation without the assistance of pre-cut kerfs. The rock excavation effectiveness of the multi-stage-cutterhead TBM can be improved by increasing the influence range of the free face.