To investigate the interaction between shield cutter and concrete, laboratory cutting experiments were carried out, which verified that the essence of cutting is the cyclic process of collision, extrusion, cutting, and peeling between cutter and specimen. The influence of tool rake and clearance angles, tool shape, cutting depth, and specimen strength on the normal cutting force F_n and tangential cutting force F_t of the tool was obtained through the cutting force testing system, and the fluctuation range of F_n, F_t and cutting force F_c under the influence of each factor was obtained through analysis. The research shows that the essence of cutting concrete with cutters was the repeated cycle of collision, cutting, and peeling, and the cutting force was always in a fluctuating state. The rake face played a major role in the rock breaking task, and the required F_n and F_t and their fluctuation decreased with the increase of the rake angle. The cutter with larger rake angle had more obvious pulling and shearing effects on the concrete. The mean value of F_n and F_t had a linear relationship with specimen strength and cutting depth. The larger the specimen strength and cutting depth were, the larger F_n and F_t were, and the smaller the fluctuation in its direction was. The effect of cutting depth on the fluctuation of F_c was greater than that of the specimen strength. The particle size of the debris increased with increasing cutting depth, while the debris at cutter tip was in powder form.