Abstract: The light bascule bridge is a new kind of bridge with an aim for reducing the weight of bascule structure. Compared with the traditional bascule bridge, the light bascule bridge chooses cable-stayed bridge without backstays as its bascule structure; therefore, the balance-weight and structure will fuse into one. Locomotive ballast, which doubles as shock absorber, is adopted to adjust the barycentre of structure to open or close the bridge. In order to lighten the weight of structure, it also uses touch-spring to assistant unseal. Starting from establishing the mechanical model of this kind bridge, the paper tries to analyze the conditions to which the design parameters of the structure must satisfy. An example is adopted to explain the primary design process of this kind bridge. Simultaneously the vibration control scheme of structure is discussed.