The bad working conditions of nonroad diesel engines have high requirements on the vibration and noise performance of the whole machine. A nonroad high pressure common rail diesel engine was used as the studying object in this paper. A multibody dynamics model for the engine was established.  Through the body and crankshaft modal testing, the accuracy of the whole finite element model and the multibody dynamic model were verified. Through establishing the valve dynamic model, the piston dynamic model and the shaft dynamics model, the main exciting force of the valve train load, the piston knock load and the main bearing load could be calculated. This paper also studied the different excitation on the machine vibration and noise. The results show that with the application of load excitation, the surface vibration velocity of the engine increases correspondingly. After loading the valve train, the vibration speed of the engine increases slightly in the high frequency range. At 500 Hz and 1 000 Hz, the influence of velocity is larger. The secondstage motivation of piston exerted greater influence on the midand highfrequency vibration of the characteristic points after loading the piston side striking force. With the increase of load excitation, the surface acoustic power level of each component basically increases. The load of the valve train has great influence on the vibration velocity of the cylinder head cover, and the piston side striking force is the main influence factor of the idle mechanical noise of the main shell parts.