［Objective］To address coal ash contamination on coal mine tunnel walls，a coal mine anti-stain varnish coating was developed by using silica sol-modified acrylic emulsion，revealingdifferences in contamination behavior between carbonaceous coal ash and conventional ash.［Methods］Based on the method A in GB/T 9780—2013 standard，a coal ash resistance evaluation protocol was established. The effects of the polymer glass transition temperature（T_g），interfacial hydrophilicity/hydrophobicity，and silica sol modification on coal ash resistance of emulsions were studied. Water contact angle meter and scanning electron microscope（SEM）were employed to analyzethe infiltration behavior and adhesion mechanisms of coal ash on organic coating，while SEM was used to observe the micro-nano structural characteristics formed by silica sol modification. Key performanceindicators such as water resistance，alkali resistance，and thermal storage stability of the anti-stain varnish were simultaneously tested.［Results］As the T_g of emulsion increased，the stain resistance of coating was significantly enhanced，carbonaceous coal ash exhibited compatibility with organic coating， resulting in increase of adhesion strength. Hydrophobic interfaces improved the stain stability bystrengthening intermolecular interactions with the coal ash，while the silica crystals generated by silicasol modification weaken the bonding strength between coating and coal ash through polar repulsion.［Conclusion］ Based on the multi-effect synergistic mechanism，the anti-stain varnish exhibited a reflectance coefficient decline rate below 5% post-contamination，significantly inhibit coal ash adsorption，and was suitable for long term protection of high coal ash polluted environments.