Abstract: Biochar is widely used in ecological restoration, agriculture and environmental protection. It is of great significance for soil remediation in environmental protection and agricultural production to develop materials that can adsorb pesticides (mainly acetochlor and atrazine herbicides) of agricultural non-point source pollutants. The biochars which had greater adsorption capacity were selected based on the analysis of raw materials and structural properties of biochars. The molecular structure of biochar, microporous structure and adsorption energy of acetochlor and atrazine were discussed by the density functional theory, and the adsorption and influence of microporous structure on pesticide molecules were studied by theoretical simulation. The results showed that the main components and pore size of plant biochar could affect the adsorption capacity of acetochlor and atrazine molecules, in which lilac-based structural lignin had the strongest adsorption ability on acetochlor and atrazine molecules. In general, the adsorption capacity was in the order of lignin﹥cellulose﹥hemicellulose, and 1 times pore size﹥2 times pore size﹥4 times pore size.