Abstract: Hydrophobicity is an important indicator to characterize the aging status of composite insulators. Because the sheds of V-string composite insulators have different inclination angles to the horizontal plane, conventional detection methods cannot be adopted to effectively detect and judge their hydrophobicity on site. In this paper, firstly, the composite insulator samples were aged by NaOH solution with a pH of 14 and a temperature of 100 ℃. The water-repellent grades of the samples after aging were obtained by the water spray classification method under the condition of an angle of 25° with the horizontal plane. A method of using a micro-injector to drop water droplets with a volume of 20 μL on the surface of the sample is proposed, which eliminates the influences of water spray angle, speed and water volume on the morphological characteristics of the water droplets in the water spray classification method. In view of the morphological characteristics of water droplets on the surface of different hydrophobic grade samples under different inclination angles, the relationship between 7 water droplet morphological characteristic parameters and inclination angle and hydrophobicity grade was studied. It is found that the inner upper angle and inner apex angle have a strong correlation. The maximum steady-state water droplet volume parameter is closely related to inclination and hydrophobicity. Moreover, a comprehensive method for determining the hydrophobicity level of V-string composite insulators is proposed. The water droplet morphology test on umbrella skirts under different inclination angles verifies the effectiveness and accuracy of the method proposed in this paper, realizing the water-repellency detection and judgment of V-string composite insulators.