Constructed wetlands (CWs) primarily achieve efficient wastewater purification through synergistic interactions among substrates, plants, and microorganisms. Serving as the structural foundation of the entire wetland system, substrates not only provide a growth medium for plants, but also serve as adhesive carriers for microorganisms and habitats for animal activities. Research on substrates has attracted considerable attention; however, in practical engineering applications, the selection of substrates often depend on personal experience, which may lead to significant gaps in the effectiveness of wetland systems in treating different characteristic contaminants. Therefore, it is of great significance to investigate the influence of substrates on the removal of contaminants in sewage and identify substrate materials with good physical and chemical properties to optimize the design and operation of CWs-based sewage-treatment systems and improve their purification efficiency. In this review, bibliometric analysis was conducted to using the Web of Science database and VOSviewer_1.6.20 software to assess the progress of research on CWs. This article provides a comprehensive overview of substrate types and characteristics based on recent research advancements in the field. Additionally, it discusses removal methods and the influence of factors related to conventional contaminants (COD, nitrogen, and phosphorus), heavy metals (HMs), fluorinated compounds, pharmaceuticals, personal care products (PPCPs), and microplastics. A thorough evaluation was conducted on the economic costs of various substrates and their ability to remove major contaminants from water bodies, providing a reference for the further development of wetland technology.