<p>Foam stability is a critical factor influencing the drainage efficiency of foam-assisted deliquification in deep coalbed methane (CBM) reservoirs. This study investigated the macro- and micro-scale stability characteristics of two foam drainage agents from a deep CBM block in China. The effects of four key parameters on macro-stability performance were investigated using static evaluation methods, including -salinity, temperature, pH, and concentration. Simultaneously, polarized light microscopy was employed to characterize microstructural features including bubble morphology, population density and size distribution, thereby elucidating the dynamic macro-micro interactions. The results demonstrated that the high-salinity conditions prevalent in deep CBM development significantly alter the interfacial tension of foam drainage agents. Experimental quantification revealed the sensitivity hierarchy of parameters affecting the drainage half-life as follows: salinity &gt; temperature &gt; pH &gt; foam drainage agent concentration. Microstructural analysis showed that bubble coarsening rates were effectively suppressed under low-temperature and neutral-pH conditions, while exhibiting accelerated growth kinetics in high-temperature, high-salinity environments, leading to compromised foam stability. Although generally consistent with macroscopic trends, certain operational regimes displayed divergent macro-micro behaviors, highlighting the necessity of multiscale investigation approaches. The established macro-micro correlations provide fundamental insights for optimizing foam-assisted deliquification operations and developing targeted defoaming strategies in deep CBM reservoirs, offering both theoretical guidance and practical significance for field applications.</p>