Abstract: Biochar-based adsorbent is one of the effective ways to remove CO2. The introduction of nitrogen source can improve the adsorption performance of biochar, but biochar still faces the defect of lacking high active adsorption sites on the carbon surface. In order to improve the adsorption capacity of biochar, the element analysis of corn straw, rice husk and chlorella was carried out. The chlorella ( 8.85 % ) with the highest nitrogen content was selected as the raw material, and the nitrogen-rich biochar was prepared by one-step activation method. The SEM-EDS characterization test showed that the metal was successfully incorporated into the surface of the nitrogen-rich biochar, and the distribution was uniform. XPS test results show that the nitrogen-containing groups migrate and transform before and after metal doping, but still mainly pyrrole nitrogen ( N-5 ). Studies have shown that metal-doped biochar reduces the specific surface area, micropore rate, and pyrrole nitrogen migration and transformation ; metal doping contributes to the chemical adsorption of nitrogen-rich biochar and CO2. The CO2 adsorption capacity of Na-doped nitrogen-rich biochar is the highest, which is 42.9 % and 16.7 % higher than that 基金项目：国家自然科学基金青年项目（52206129）；中国博士后科学基金特别资助项目（2024T170362）；中国博士后科学基金面上项目（2023M731426） 作者简介：邹帅（2001—）,男，吉林通化人，硕士研究生。研究方向：低碳清洁燃烧。E-mail：958808722@qq.com 通讯作者：陈萍（1990—）,女，安徽马鞍山人，副教授，博士。研究方向：低碳清洁燃烧。E-mail：chp0109@126.com of nitrogen-rich biochar and Zn-doped nitrogen-rich biochar, respectively. The molecular mechanism of CO2 adsorption by Na, Zn coupled N-5 was studied from the theoretical calculation level of quantum chemistry.The theoretical calculation results show that the adsorption energy of CO2 on CN5 @ Na2O surface is 24.98 kJ / mol higher than that of CN5 @ ZnO.Metal doping is beneficial to promote the adsorption of CO2 and the promotion effect of Na is better than that of Zn.