Based on the design proposal of twin balancer shafts system in some type of 4-cylinder in line internal combustion (IC) engine, a multiple body dynamical model of engine powerplant is constructed using a famous commercial software of AVL Excite PU to estimate noise and vibration of powerplant. The influence of mating force between crankshaft gear and balancer shaft gear on rotate speed and impact force acting on journal bearing is analyzed, and then the comparison of vibration response of engine block between the case of with balancer shaft and the case of without it is carried out. Finally, Based on the translate path analysis (TPA), the effect of balancer shafts on 2nd order vibration of engine powerplant mount and 2nd order vehicle interior noise is investigated. The simulation results shown the fact that it is helpful to improve the NVH ability of powerplant and to reduce interior sound pressure level by installing twin balancer shafts system into IC engine.