With the rapid development of economic globalization, the amount of sludge discharged from municipal wastewater treatment is increasing, and the annual production of municipal sludge is expected to exceed 90 million tons by 2025 in China. The pathogenic microorganisms, organic matter and heavy metals contained in municipal sludge can cause serious harm to the environment and human health. Due to its large specific surface area, excellent pore structure and rich oxygen-containing groups, sludge-derived biochar materials are widely used in wastewater treatment, achieving the dual purpose of solid waste reuse and pollution removal. In addition, a win-win situation of ecology and development by treating waste with waste can be obtained. So the preparation and modification methods of sludge biochar is systematically summarized, its application to heavy metals, dyes, inorganic salts, antibiotics and phenols in wastewater and its adsorption mechanism are also reviewed in the paper. And the future development and the problems to overcome are also prospected, Green low-carbon resource treatment system will be tried to form.