Considering the stiffness of elastic bearing, the frequencies and modal of the bridge with elastic bearing were studied. The first two frequencies were compared, and the regularity of frequencies change with stiffness of elastic bearing was obtained. Using modal superstition principal, the first two modal were used for analyzing the response of bridge with elastic bearing under moving load. The first modal of bridge with elastic bearing includes the rigid body translation and the first modal of simply supported beam. The second modal of bridge with elastic bearing includes the rigid body rotation and the first modal of simply supported beam. The solution obtained with two modals differs widely from that with only the first modal. Especially, when the vehicle is simulated as a spring-mass system, the coupling force has wider difference.