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The change of the feeding amount will cause the various working parts to be subjected to variable load impact and unbalanced force, resulting in a sudden change in the vibration of the combine harvester when it is working. Aiming at the stability and reliability of the combine harvester, based on the combine harvester motion balance equation and the correlation analysis method of the external vibration disturbance signal, the vibration acceleration signal of the main working parts under different feeding amounts was obtained by carrying out the variable feeding vibration test of the combine harvester under field conditions. When the fed grains exhibited strong damping characteristics, the vibration acceleration signal was decreased accordingly. However, when the power demand of the harvester was increased, it would further lead to the phenomenon of increased vibration signal. The acceleration signal measured by the test was processed by quadratic integration, and the acceleration signal was converted into a frequency domain signal by fast Fourier transform. The change of amplitude and the characteristics of excitation frequency were obtained. The vibration caused by the disturbance of the feeding amount mainly occurred in the low frequency excitation frequency range, and the damping characteristic of the feeding amount reduced the high frequency amplitude. The feeding amount had the most obvious effect on the vibration of the threshing drum, and the maximum amplitude was attenuated from 17μm to 2.8μm, and the change degree could reach 83.5%. The change degree of header and the conveying trough was 55.8% and 7.69%, respectively. The maximum peak point of the threshing drum also moved left from the mid-frequency near 195Hz to the low-frequency near 117Hz.