Abstract: In order to study the relationship between leakage current and composite insulator surface with corrosion product fouling, samples are prepared by artificial pollution test method, and the leakage current testing equipment are used to measure the leakage currents of samples by taking the pollution time, salt density, ash density and pH value as variables, and the influences of the variables on the leakage current are analyzed. The results show that the leakage currents on the composite insulator surface increase with the corrosion time, and the influence on leakage currents in the acidic environment is greater than that in alkaline environment; compared with ash density, influence of salt density change on the leakage current is more obvious, and the leakage current increase with the increase of the voltage and the applied voltage time.