An effort has made to describe how the dynamic analysis of Finite Element model of trolley of Ground Power Unit (GPU) of Jaguar and Mirage-2000 aircrafts which is four wheeled light motor vehicle used to boot or start the aircrafts in Indian air force. The full transient dynamic analysis is used in ANSYS8.0 for GPU analysis. The dynamic behavior of existing design of chassis of GPU is carried out at different road conditions, different velocities with respective to negotiation of rigid wheels. This analysis is performed by considering four different cases of wheels falling into the ditches. The four standard sizes of ditches are provided the road conditions. The uniform chassis material and linear behavior of the leaf spring and dampers are considered during the analysis. The trajectory of center of the wheel provides the accelerations, vertical displacements(UY) and horizontal displacements(UX) with respective time. The dynamic behavior of the chassis of GPU is simulated in the form of maximum stresses developed in the chassis, maximum relative deflection and absolute deflection at each node of chassis subjected to the various ditch sizes, velocities and cases of wheels falling.