Abstract: Ion−adsorption rare earth ores, an important source of rare earth elements, are used in a wide range of applications. The in−situ leaching process is the primary method for extracting ionic rare earth minerals. In this process, high concentrations of ammonium sulphate are used as the leaching agent to extract rare earth elements. However, the extensive use of high concentration ammonium sulfate leaching agents has led to a number of environmental problems, resulting in severe ammonia nitrogen pollution in the soil and water bodies in and around the mining areas. This contamination not only disrupts the local ecological environment but also poses a potential threat to the surrounding ecosystems and the living conditions of the residents. This review summarizes the sources and detrimental effects of ammonia nitrogen pollution within ion−adsorption rare earth mining regions. Elevated ammonia nitrogen (NH₄⁺−N) concentrations in soils not only diminish soil fertility but also potentially initiate soil acidification and degradation processes. Furthermore, excess ammonia nitrogen in aquatic systems compromises the functionality of water resources, thereby contaminating water bodies and reducing their suitability for agricultural irrigation, industrial applications, and domestic consumption. The article further elucidates the occurrence of ammonia nitrogen in the mining environment, including its aqueous, fixed, and ion−exchangeable states. These three states of existence dictate the migration and transformation patterns of ammonia nitrogen within the environment. Aqueous ammonia nitrogen is prone to migration via water flow, thereby increasing the extent of contamination. Fixed ammonia nitrogen, conversely, exhibits relative stability, although it may be released under specific conditions. Ion−exchangeable ammonia nitrogen can undergo displacement reactions with other ions through ion exchange, consequently influencing its behavior and distribution within the environment. To effectively address ammonia nitrogen pollution in ionic rare earth mining areas, this paper systematically reviews various remediation technologies. Regarding the treatment of ammonia nitrogen pollution in mine water bodies, heterotrophic nitrification−aerobic denitrification (HN−AD) processes and microalgae treatment methods are introduced. The HN−AD process is a highly efficient biological treatment technology that utilizes microbial activity to convert ammonia nitrogen into nitrogen gas, thereby achieving ammonia nitrogen removal. Microalgae treatment methods leverage the absorption and utilization capabilities of microalgae for ammonia nitrogen, converting it into biomass through photosynthesis, while also generating oxygen to improve the water environment. For the remediation of ammonia nitrogen pollution in mine soils, mineral material remediation and chemical leaching methods are presented. Mineral material remediation involves the addition of specific mineral materials, utilizing their adsorption and ion exchange properties to immobilize ammonia nitrogen in the soil, thereby reducing its mobility. Chemical leaching involves the use of chemical leaching agents to dissolve and elute ammonia nitrogen from the soil, thereby achieving soil purification. Through this comprehensive review of the current state of research, this paper aims to identify suitable solutions for the remediation of ammonia nitrogen pollution in the soil and water from rare earth tailings, thereby mitigating their adverse impacts on the natural environment.