The invention relates to a method for analysing the operating state of a cutting unit (1) for mowing harvested material, wherein the cutting unit (1) has at least one mowing knife (2, 2') that is driven back and forth in a stroke direction (H) and the mowing knife (2, 2') has cutters (23, 24) which cooperate with shear bars (25, 25', 26, 26') of the cutting unit (1), having the following method steps: sensing a signal representing the stroke position of the mowing knife (2, 2'), sensing a signal representing the knife force (29) for driving the mowing knife (2, 2'), depending on the stroke position, and determining harvested-material and/or cutting-system properties from an evaluation of the signal representing the knife force (29) depending on the stroke position.
