Biochar modification is an effective technique for adsorbing nitrogen from wastewater.  The adsorption mechanism of biochar for nitrogen in water bodies were introduced, focusing on the modification methods of biochar, including physical methods such as high-temperature calcination, mechanical ball milling, microwave treatment, steam activation; chemical methods such as acid modification, alkali modification, oxidant modification, metal loading modification, and biological methods assisted by microorganisms. The factors affecting the adsorption of modified biochar for nitrogen in water bodies and looks forward to the future research directions and production applications of modified biochar for nitrogen adsorption were summarized.