The invention discloses a method using hydrophobic migration tests to judge silicone rubber aging degree.The method includes: cutting off an insulating umbrella skirt from a root to prepare a test piece or scraping up RTV coating along an insulator, cleaning the natural dirt on the surface of the RTV coating, and placing in a room-temperature environment for 7 days; coating with artificial dirt with the same pollution degree and components; starting the hydrophobic migration tests, performing one hydrophobic migration test every other 12 hours in the first 96 hours, and performing one hydrophobic migration test every other 24 hours in the 96-196 hours; drawing hydrophobic migration curves for evaluating the performance and aging degree of silicone rubber.The method has the advantages that the curves are used for qualitatively evaluating the performance and aging degree of materials, the operation performance of the composite insulator and the RTV anti-pollution flashover coating can be reflected accurately, and advices are provided for the application strategy of the composite insulator and the RTV anti-pollution flashover coating; the method is simple, convenient to operate and capable of increasing work efficiency.