The invention discloses a bridge drainage system, which comprises a bridge body, bridge drainage pipelines and vertical drainage pipes. Vertical bridge columns are mounted below fixing columns which are mounted below the bridge body, bridge protective fences are mounted above the bridge body, the bridge drainage pipelines are mounted in the bridge body, and spiral devices are mounted in the bridgedrainage pipelines. The vertical drainage pipes are mounted below connection pipes which are mounted below the bridge drainage pipelines, and drainage system fixators are mounted outside the verticaldrainage pipes. By mounting of filter windows in the bridge, water-insoluble blocks can be filtered out and prevented from blocking the pipelines; by mounting of the spiral devices in the pipelines,water flow direction and speed can be changed, water flow impact is reduced to protect the pipelines from being damaged by strong water flow, more cost is saved, and service lives of the pipelines ofthe drainage system are prolonged.