142.6 Hz、56.6 Hz、36.6Hz、36.6 Hz。Based on the characteristics of vibration source of wheat combines, the dynamic responses of the testing spot on the floor of main driver's seat of Xinjiang-2A combine were measured by DH5922 dynamic state signal testing and analyzing system. The timing-process curves of vertical vibration acceleration and the spectrum of Fourier fast transform on the testing spot were achieved under the four working conditions of the combine that included idling, the engine idling, the combine working in the fields and the combine transporting on the highway. The results showed that vibration strength and frequency structure of any spot of the combine are different with the different working conditions. The root-mean-square values of the vibration acceleration of the testing spot under the four working conditions were 0.1591 m/s2,0.108 7 m/s2,0.0938 m/s2 and 0.0704 m/s2 respectively, and the dominant vibration frequencies were 142.6 Hz, 56.6 Hz, 36.6 Hz and 36.6 Hz respectively.