The invention discloses a cutting force measurement method based on a machine tool main shaft-shank-cutter mode coupling technology for solving the technical problem of low measurement precision of a traditional cutting force measurement method. Firstly, a measurement point of a displacement sensor is selected in the vertical direction of a cutter rod; and the displacement sensor is fixedly mounted in the selected position. Then, the deformation and the displacement of the measurement point of the cutter rod in the idling and machining process are respectively acquired, and are subtracted to obtain actual deformation and displacement in the measurement point of the cutter rod. Finally, the cutter rigidity is determined by using a structural mode coupling technology to calculate the cutting force. Displacement and deformation signals of the measurement point P of the cutter rod are respectively acquired in the idling and machining process; actual displacement and deformation signals delta c-delta ac of the measurement point P of the cutter rod are determined; then, the rigidity K delta in the measurement point P of the cutter rod is determined by using the structural mode coupling technology; and finally, K delta and delta c-delta ac are multiplied to obtain the cutting force. Compared with a background technology, the obtained cutting force is more accurate.