The invention relates to a roof flushing device, and belongs to the field of environmental protection. The roof flushing device aims to achieve the purposes that the roof pollution is removed, a roof is kept clean and tidy, and dust and other pollutants on the roof are prevented from being detained on the roof for a long time and badly pollute the air when being kicked up in the strong wind weather. The roof flushing device structurally comprises an upper water pipe, a valve, a spraying head, a dirt discharge trench and a dirt discharge pipe. According to the working principle, the tap water in a building is led to the spraying head on the roof, the roof is sprayed with the water and flushed through the spraying head to flush the dust and other pollutants on the roof to the dirt discharge trench, the dust and other pollutants on the roof are discharged to the underground through the dirt discharge pipe, and the purpose of removing the roof pollution and keeping the roof clean and tidy are achieved. At present, the roof pollution is one of the important factors of urban pollution, so that the floor pollution treatment work should be done well while other aspects of works are done well, the floor flushing device is the best selection, and the technology of the floor flushing device is simple and practical and low in cost and plays an active role in solving the urban pollution problem.