Abstract: The random vibration of a coupled vehicle-bridge system with sprung masses under moving vehicular loads is studied. The mode shapes of the bridge with sprung masses are obtained. The vehicle is modeled as a two-DOF system with linear suspensions and tire flexibility. The power spectral density of the bridge's surface irregularity is taken as input. According to the state space theory and the general evolutionary random processes, the controllable method of analyzing the random response of the coupled system is derived. The numerical studies show that the sprung masses have no effect on the random response of the vehicle, but the random response of the bridge is reduced. The effects of the mass ratio μ, the quantity of sprung masses on the random response of the coupled vehicle-bridge system are discussed.