Abstract: The problem of pesticide pollution is becoming increasingly prominent. When pesticides are used in excess of safe usage standards or is widely promoted in agricultural production, they can have toxic effects on organisms and lead to soil and water pollution. Therefore, there is an urgent need for economical and effective raw materials or technologies to reduce the negative impact of pesticides. Biochar has a the characteristics of high specific surface area and pore volume, as well as abundant functional groups on the surface, which can be used for adsorbing pesticides. It is also low-cost and highly efficient. The adsorption capacity of biochar for pesticides is limited, but this can be improved through modification. This paper systematically reviewed the preparation, characteristics, and formation mechanisms of biochar, with a focus on the mechanisms of chemical modification, physical modification, and biological modification of biochar, as well as their research progress in pesticide adsorption. The mechanisms of modified biochar on pesticide adsorption were summarized, and the research prospects of biochar on pesticide adsorption were discussed. This work provides a theoretical basis for optimizing the performance of biochar and reducing pesticide pollution.