<p>Transmission line insulators are susceptible to algae contamination in humid environments, resulting in decreased surface hydrophobicity and deterioration of insulation performance, which in turn leads to electrical accidents such as leakage current and flashover\. To overcome this problem, in this study, stearic acid was used to modify the surface of nano-TiO₂, and composite coatings with different ratios were prepared. The photocatalytic algae inhibition performance and electrical insulation performance of the coating were evaluated by scanning electron microscopy, contact angle, resistivity, and dielectric loss tests. The results showed that the stearic acid modification significantly improved the dispersibility and hydrophobicity of TiO₂, among which the sample with a mass ratio of 1:5 (TWC₁) had the best performance. After 96&#xa0;h of algae coverage, the contact angle of TWC₁ decreased by only 30.96%, and the algal cell concentration increased by only about 15%. The surface resistivity decreased by 31.76%, and the dry and wet flashover voltages decreased by 11.13% and 22.68%, respectively, which were better than those of glass and unmodified samples. This composite coating exhibits excellent performance in both photocatalytic algae inhibition and improvement of electrical properties, providing a feasible approach for algae inhibition on transmission line insulators.</p>