Abstract: Utilizing high-concentration carbon source flue gas to enhance coalbed methane development is regarded as an effective measure to address the excessive costs of CO₂-ECBM injection. However, the impact of associated gases co-injected with CO₂ into deep reservoirs on resource recovery and long-term sequestration safety requires urgent resolution. The core issue lies in clarifying the mechanism by which impurity components affect the reservoir pore-fracture network under CO₂ storage conditions. As a typical NO_x pollutant in flue gas, NO exhibits significant chemical activity and poses severe hazards to the environment and climate. Therefore, the influence of supercritical CO₂ containing different volume fractions of NO on the pore structure and sequestration capacity of anthracite reservoirs is investigated. High-rank anthracite from the Guizhou region is selected as the research object. Under reservoir conditions of 40 ℃ and an injection pressure of 10 MPa, the microscopic pore structure, surface morphology, and mineralogical evolution characteristics of the anthracite are systematically characterized by combining LT-N₂, NMR, XRD, and ESEM. Results indicate that the presence of trace NO inhibits the modification effect of CO₂ on the pore structure of anthracite. When the NO volume fraction in the flue gas is 500×10⁻⁶, the porosity increase rate attenuation reaches 50%; beyond 4 000×10⁻⁶, the inhibition rate stabilizes at 63%. By competing with CO₂ for surface active sites and forming a stable chemisorption state, pore throats are directly physically blocked by NO. However, the seepage porosity generally exhibits a pore-expansion trend, and the connectivity and seepage capacity of the pore network are not systematically deteriorated. Due to the smaller molecular diameter of NO compared to CO₂, adsorption sites in micropores preferentially adsorb NO, forming a molecular sieving effect that hinders CO₂ entry. In mesopores, NO tends to interact with oxygen-containing functional groups on the coal matrix surface, interfering with the adsorption stability of CO₂ at polar sites, thereby indirectly reducing the quantity of adsorbed CO₂. Mesopores are found to be more sensitive to the NO inhibition effect, approximately 2.2 times that of micropores. Nevertheless, as the NO volume fraction in flue gas is low, the inhibition effect is limited, and the total porosity of anthracite treated with NO-CO₂ still shows an increasing trend compared to the untreated state. Based on the inhibitory effect of NO on the ability of CO₂ to modify the anthracite pore structure, a staged regulation strategy for flue gas-enhanced coalbed methane recovery and sequestration technology is proposed. In the initial stage, NO-rich carbon-source flue gas (φ(NO)≥ 500×10⁻⁶) is selected to inhibit coal matrix swelling and mitigate the decline in permeability around the wellbore; in the middle and late stages, the concentration is reduced to below 500×10⁻⁶ to achieve reservoir modification and CO₂ sequestration effects. Theoretical support for the optimization of the CO₂-ECBM injection process is provided by these research findings.