Abstract: The weatherability of heavy-duty coating modified by rutile nano-TiO₂ was tested. In the conditions of different nano-TiO₂ ratio and different aging time, the examination results of heavy-duty coating modified by ultra-fines demonstrate that the compound nano-coatings can prevent the resin from oxidizing efficiently, prolong the coating's service age, and so improve the weatherability of coating. The modifying capability of ultra-fines is proportional to its amount in the coating. The absorption spectra of ultra-fine titanium dioxide powders confirme that nano-TiO₂ can absorb 95% of the ultraviolet light in UV spectrum.