The invention relates to the field of insulating materials and particularly relates to an insulating tape which consists of a base layer and a viscose layer, wherein the base layer is obtained by impregnating double-layer gauze with a base-layer glue solution and then drying the double-layer gauze; and the base-layer glue solution comprises the following raw materials in parts by weight: 10-15 parts of 10# asphalt, 10-15 parts of 70# asphalt, 10-12 parts of epoxy resin, 3-5 parts of pigment filler and 1-3 parts of hydroxyl-terminated hyperbranched polymer. With a gauze base, the foundation of the base layer is firm, and the aging resistance and weather resistance are enhanced; in the base-layer glue solution, the asphalt is compounded with the epoxy resin; and in order to enhance the bonding property with the gauze, the hydroxyl-terminated hyperbranched polymer is added, and the base-layer material has higher firmness, acid-alkali resistance, insulating property and aging resistance while the service life is prolonged.