Abstract: Biochar has become a prominent material to improve the efficiency of ecological treatment processes due to its well-developed pore structure, abundant surface functional groups and cost-effectiveness. Employing the bibliometric method, this study systematically analyzes the research progress of biochar application in ecological treatment processes based on Web of Science core database from 2015 to 2024. By reviewing the literature on typical processes such as constructed wetlands, biofilters and ecological ditches, the enhanced removal efficiency of conventional pollutants (chemical oxygen demand, nitrogen, phosphorus), heavy metals, and emerging pollutants by biochar is summarized. Furthermore, the synergistic purification mechanism of biochar-based materials in ecological treatment processes through physicochemical effects such as adsorption, catalysis, and ion exchange, combined with biological effects of microbial community regulation, is discussed. The results show that the number of research papers in this field has been increasing in the past 10 years. The current research focuses on the application of biochar in constructed wetlands and biofilters, while the application research in ecological ditches is relatively weak. The research content focuses on enhancing the efficiency of ecological treatment processes by using biochar modification and compounding with other fillers as the core. The quantitative analysis of the existing literature data shows that, compared with the traditional substrates, the median removal rates of chemical oxygen demand, total nitrogen and total phosphorus are increased by more than 10%. The enhancement in ammonia nitrogen removal is relatively limited (median increase: 4.46%-7.80%), while the removal rate of various heavy metals is increased by 6.11%-22.70%. These improvements are primarily attributed to the adsorption mechanism of biochar itself and its regulatory effects on plants and microorganisms, thereby boosting the efficiency of ecological treatment processes. Finally, the study discusses key challenges and future research directions, including the unclear mechanisms governing the fate of emerging pollutants, insufficient understanding of the interactions at substrate interfaces with compound pollutants, the lack of long-term operation and low temperature adaptability of systems, and practical engineering applications.