As a multi-excitation source vibration system in a complex farming environment, the vibration mechanism of the silage corn harvester is difficult to be thoroughly described theoretically. To investigate the analysis methods suitable for studying its vibration characteristics, a silage corn harvester test bench was built in this paper. A 24-bit INV3062-C1(S) general-purpose dynamic test and acquisition instrument was used to test the vibrations of the kneading roll, the fixed knife, and the frame position at different speeds. The mean, variance, and RMS values of the vibration amplitude of the test bench were analyzed. The vibration signal could be approximated as conforming to the characteristics of smooth random vibration. The time-domain characteristics and vibration frequency distribution law of the vibration under different working conditions were obtained. The results show that with the increase of motor speed, the vibration intensity of the whole machine increases, among which the vibration amplitude of the kneading roller position is the largest, the frame is the second, and the fixed knife is the smallest. Under the straw feeding condition, with the increase of speed, the rate of the frame amplitude is higher than that of the kneading roller and fixed knife, and the frame is the most sensitive to the change of motor speed. The influence of corn straw feeding on the vibration of the test bench is larger at low speed (900 r/min) and medium speed (2 000-4 000 r/min), and less at high speed (4 500 r/min). The vibration frequency of the test stand is concentrated in the range of 166.7-185 Hz, 250.7-269.6 Hz, 527-559 Hz, 746.8-776.2 Hz, and 872.9-904.8 Hz, which is mainly the multi-frequency component of the motor rotation frequency. At medium and high speed, the vibration of the motor has a greater impact on the vibration of the test stand and has less impact in the low-speed state. In the design of silage harvester, consideration can be given to arranging reinforcement bars at the frame position and adding vibration isolation between the silage harvester frame and the engine to reduce the impact of vibration on the silage corn harvester. The study results can provide a reference for reducing the vibration of the whole machine of the silage harvester and for the design and optimization of the harvesting machine in the complex farming environment.