Based on elastic dynamic model, an elastic dynamic controllable model of the vehicle flexible robot system was established. Regarding the low-order modes as the control modes, setting the boundary coordinates in the locations of the hydraulic actuator, the controllable state-space equations of the system was formed. A precondition for realizing system’s precise control is that the system is controllable. According to system’s controllability discriminant qualification, the influence of physical parameters on the controllability of system got broad discussed, and some reference data was obtained, which would be helpful for the next step to control the vibration. Aiming at the interference of the state-space equations, disturb distributing matrix was merged with input matrix, disturb vectors was merged with input vectors, a new state-space equation was established. By dynamic simulation, vibration response of the vehicle flexible robot system was achieved, and the experimental results showed that the treatment about disturb distributing matrix is feasible.