As an important part of transmission lines, composite insulators are susceptible to aging and failure due to contamination, UV and other factors during operation, leading to flashover accidents. This paper studies the aging characteristics of composite insulators and anti-pollution flashover coatings operating in coastal areas of Fujian province with different ages. The physical and chemical properties were characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), water contact angle (WCA) and volume resistivity. The results show that the content of Si-O bond and Si-CH₃ bond, hydrophobicity and surface roughness can be used to evaluate the aging degree of insulators.