Abstract:Filler is the core component of the constructed wetland system and also the key factor affecting the pollutant purification ability of the constructed wetland system. The selection of suitable fillers is very important for the construction of constructed wetland system and the purification of wastewater. Firstly, the role of fillers in the constructed wetland system was described. Secondly, the characteristics and selection principles of fillers suitable for the construction of constructed wetlands were analyzed. Finally, the current research progress through filler modification, preparation of slow-release carbon source fillers and the use of composite fillers to strengthen the purification of pollutants in the constructed wetland system were summarized, and the future research direction was proposed. It can provide references for the construction and promotion of constructed wetlands.