The invention relates to a sanitation system of a building, in particular to a temporary sanitation system in the building. The temporary sanitation system of the building comprises a water supply device and a water outlet pipe, wherein the water outlet pipe is communicated with the water outlet end of the water supply device, a pipeline, arranged on the side of building, of the water outlet pipe climbs upward along the temporary wall surface, specially built for the temporary sanitation system, of the building, the positions, branch pipes which are communicated with the water outlet pipe are arranged at the positions of each floor, and the other end of each branch pipe is connected with a sanitation facility. The temporary sanitation system of the building is low in cost, environment-friendliness and convenient to assemble and disassemble.