The installing and driving environment model of diesel power unit was built by using vehicle dynamics software, and four road models including paved road, wave-typed road, D-staged road and slope road were established according to application scenes. Based on the established vehicle and road models, the vibration characteristics for diesel power unit under different road conditions were studied. The results show that the vibration peak and frequency band distribution of diesel power unit are influenced at different degrees by different surface characteristic roads. The order of maximum peak for diesel power unit is D-staged road, wave-typed road, slope road and paved road during the velocity-increasing process of starting on four kinds of roads. According to the peak-peak value, the vibration of wave-typed road, D-staged road and slope road are equivalent and the vibration of paved road is the smallest. According to the frequency spectrum, the frequency bands of wave-typed road, D-staged road and slope road are relatively concentrated and that of paved road is approximately even. During the normal driving of vehicle, the vibration of slope road is larger than that of the other three roads.