The excitation of uneven road will transfer to the engine through the vehicle wheel and body during the driving, which mixes with the generated vibration excitation of engine operation and ultimately transfers to the turbocharger. These excitations are collectively referred to as external excitation. External excitation acts on the turbocharger housing and bearing body and then transfers to the shaft through two floatingring bearings, which affects the stability of the turbocharger shaft system. In order to solve the problem, the finite element analysis method was used to establish a multi-body dynamic model of turbocharger assembly. The vibration response of shaft system was then simulated on the vibration test bench when the turbocharger assembly was subjected to external excitation from the engine.The 0.5 times, 0.25 times, and 0.125 times of original signal and itself were applied respectively. The vibration response of shaft system showed a corresponding linear pattern. The transfer functions obtained by four vibration signals were basically consistent. The simulation accuracy of finite element model was verified through the vibration test bench experiment. The experimental results were consistent with the simulation results in 0-800 Hz frequency range, which verified the feasibility of using the finite element method to calculate the vibration response of shaft system. Accordingly, a new solution was provided to solve the vibration problem of turbocharger shaft system.