Bridge hierarchical drainage system applied to steel bridge deck

The present invention relates to a bridge hierarchical drainage system applied to a steel bridge deck and belongs to the bridge drainage field. The bridge hierarchical drainage system comprises drainage shallow channels, a plurality of vertically-arranged direct drainage pipes and centralized drainage pipes; the drainage shallow channels are located at two sides of the bridge deck; the water inlets of the direct drainage pipes and the centralized drainage pipes are located in the drainage shallow channels; the water inlets of the direct drainage pipes are higher than the groove bottoms of the drainage shallow channels and are lower than the groove surfaces of the drainage shallow channels; the water inlets of the centralized drainage pipes are lower than the groove bottoms of the drainage shallow channels; a water collection pipe distributed along the direction of a bridge is arranged at the lower side of the bridge deck; the lower ends of the centralized drainage pipes are connected with the water collection pipe; and the water collection pipe is connected with a wastewater treatment tank. With the bridge hierarchical drainage system of the invention adopted, rainwater on the deck can be quickly drained.