The invention discloses a curtain wall cleaning system, and belongs to the technical field of cleaning devices. The curtain wall cleaning system comprises a monitor, cleaners, a central control part, a cleaning liquid pump, a cleaning liquid pool, a clean water pump, a clean water pool, a filter, a sewage pump and water collecting devices. The cleaners are connected with the cleaning liquid pump and the clean water pump through pipes respectively, and a water outlet of the clean water pool is connected with a sewage draining opening through the filter. The multiple water collecting devices are arranged on a curtain wall, connected with the filter through the sewage pump and connected with the clean water pool through the filter, and the filter is further connected with the sewage draining opening to drain sewage. The cleaning liquid pool is connected with a water inlet. The central control part is connected with the monitor, the cleaners, the cleaning liquid pump, the clean water pump, the filter, the sewage pump and the water collecting devices through power supply and communication cables. According to the curtain wall cleaning system, a sewage collecting and filtering system is adopted, collected rainwater, cleaning water and the like can be filtered, stored and reused, and the aim of energy saving is achieved. Manual work is completely replaced through the automatic cleaners, and the potential safety hazards of a person are completely avoided.