Abstract: As a renewable and environmentally friendly multifunctional carbon material, biochar exhibits excellent adsorption capacity, well-developed pore structure, and chemical stability, making it highly promising in pollution control, soil improvement, and sustainable agricultural development．Biochar's major preparation methods, including pyrolysis, gasification, and hydrothermal carbonization, and effects of key parameters on its material properties were reviewed systematically．And role of chemical, physical, and composite modification techniques in optimizing biochar performance was explored．Additionally, biochar application in water pollution control, heavy metal removal, soil improvement, agricultural efficiency enhancement, and other emerging fields were analyzed in detail, along with an overview of technical research bottlenecks, such as long-term environmental impact, large-scale production costs, and industrialization promotion issues．Proposals were also put forward for biochar future development, focusing on low-carbon and efficient preparation technologies, multifunctional modification strategies, long-term ecological safety assessments, and market promotion models optimization, to facilitate biochar broader application in environmental governance and green low-carbon development．