Abstract: High efficiency adsorbents are one of the effective ways to reduce NOx and CO2 emissions. In this study, rice husks were used as raw materials, modified and activated by urea and CaO, and the effects of different nitro-containing biochar and CaO-coupled nitro-doped biochar on NO, CO2 and their synergistic adsorption properties were investigated by combining experiments and density functional theory calculations. The experimental results show that nitrogen-containing porous carbon is mainly microporous, and its urea mixture can promote the formation of biochar pores. The specific surface area of BC1-2 is 1491.30 m2/g, and the microporosity is 72.5%. The theoretical calculation results showed that the adsorption capacity of NO and CO2 decreased with the increase of temperature, and the increase of pyrrole nitrogen biochar (CN-5) was more conducive to gas adsorption, and CaO coupling with CN-5 could further increase the gas adsorption capacity of biochar. The adsorption capacity of CN-5 for NO and CO2 increased by 143.88% and 13.75%, respectively, compared with that of pure biocharcoal. CaO/CN-5 had more obvious improvement performance than CN-5, and its adsorption capacity for NO and CO2 increased by more than 5 times compared with CN-5. At 273K, the adsorption capacity of NO and CO2 by CaO/CN-5 system was 0.134mmol/g and 1.458mmol/g higher than that by CN-5 system, respectively. The adsorption capacity of CN-5 and CaO/CN-5 on NO@CO2 increased by 123.9% and 514.97%, respectively, compared with that of pure biocarbon.