The invention relates to the technical field of electric power facility, and especially relates to an insulator. The insulator is composed of internal layer foam glass and an isolation layer coated outside the foam glass, and a silane coupling agent layer is arranged between the foam glass and the isolation layer. Polytetrafluoroethylene cannot be individually used as an insulator material due to the cold flow property, arrangement of the foam glass in polytetrafluoroethylene solves the above problem, and the foam glass has moderate (not too large or not too small) density, so requirements of a supporting part are effectively reduced, and the stability of a line is increased; and the isolation layer and the foam glass have the advantages of very good insulation property and hydrophobicity, strong weatherability and long service life, and the isolation layer is easy to clean, and can save the cleaning cost in the use process.