Abstract: In some northern regions of China, water shortage has caused rivers to dry up. However, rainfall resources are abundant in summer. Although runoffs are subject to pollution to a certain extent, they are less polluted with simpler composition compared with domestic sewage and industrial wastewater. Rainfall can be well purified through the constructed wetland purification system with low operation cost to enrich river landscape and replenish water ecologically. It is more appropriate for urban fringe areas, where the pipe network’s heavy rain-bearing capacity is overloaded, to adopt the artificial water purification system to diverse rainwater in the sewage and reduce the pressure of the drainage system in the urban construction and renewal process. The artificial wetland area can be determined and checked by using the ammonium loading rate (ALR). This study integrates three main processes of artificial water purification: pretreatment unit, constructed wetland unit and disinfection storage unit, based on which the intelligent control system of Internet of Things technology is introduced to achieve low operating costs, low management costs and optimal net water quantity. The whole process has multiple advantages including all levels of effluent water quality monitoring, multi-level controlling, ecological water purifying and landscaping, to make purification effects meet the standards of river water quality requirements. The process provides new ideas for alleviating river water shortage in northern cities and solving the urban rainfall flood problem.