The invention discloses a spraying device used on an asphalt distributor or a road sprinkler, and provides a spray-tube spraying device capable of selecting a nozzle according to a using condition and automatically controlling a switch synchronizing with the selected nozzle, and solves the technical problems that the asphalt distributor or the road sprinkler consumes a large amount of energy whenin spraying and cannot be used in special occasions such as narrow roads requirement for local spraying operation and the like in the prior art. The spray-tube spraying device comprises a horizontal spraying rod, the horizontal spraying rod is connected with a liquid storage tank through an input pipeline, a plurality of nozzles with valves are arranged on the horizontal spraying rod, the plug ofeach valve is movably connected to a guiding rod, and the guiding rod is driven by a cylinder to drive the valves to be opened or closed simultaneously.