The utility model relates to an open-closed on-water boat float bridge which comprises a steel plate bridge body, a conjuncted pontoon, a track fixing frame, a slide rail, a console and a motor drive mechanism. The conjuncted pontoon comprises a plurality of single pontoons on the left and the right banks of the pontoon which are concurrently and horizontally connected; the conjuncted pontoon is connected with the steel plate bridge body at the upper part; the conjuncted pontoon and the tail end of the steel plate bridge body are fixed on the slide rail; a bridge tail building body and the console are arranged outside the track fixing frame; a hanging hook is respectively arranged at the head and the trail ends of the track fixing frame; an upper positioning point and a lower positioning point are respectively arranged at the head and the tail ends of the slide rail; and a main control unit is arranged inside the console. The utility model has the advantages that the float bridge can be opened and closed automatically through the control system at different times, the contradiction generated between tourist industry and water transportation industry is solved, so that the economic efficiency is improved; and the utility model saves time and labor, as well as raw materials, and improves the work efficiency, and has wide extendable space in application.