This paper reports on an investigation of articulated dump trucks vibration analysis and rear suspension stiffness sensitivity analysis. Since the frame of the off-highway dump truck is integrated, the impact from the road surface against the rear wheel is transmitted to the cab directly through the hydro pneumatic suspension and the frame, and finally contributes to the ride comfort. Articulated dump trucks are different from rigid-frame off-highway dump trucks, with the frame divided into two parts and jointed by a hinge, which forms two degrees of freedom between the two parts. Compared with rigid-frame dump trucks, the impact from the road surface against the rear wheel of the articulated truck would not transmit directly to the cab through the frame for the attenuation effect of the hinge. This paper studies the truck mass centre vibration characteristic which shows the resonance frequency of the articulated dump truck. The excitation transmitted to the cab through different rear suspension spring stiffness has also been studied to obtain the impact on the cab vibration. A three-dimensional model of an articulated dump truck is established to study the response to different road profiles and rear suspension spring stiffness.