The utility model relates to an insulator among the electric power system, specifically be one kind can make up, the rod insulator of split, including claviform core bar and one big one little full skirt insulating sheath, core bar one end link fitting, gold utensil tip outer wall interval is equipped with at least three boss, the core bar other end is equipped with internal diameter and gold utensil tip external diameter matched with connecting hole, be equipped with to connecting hole inner wall interval the axial notch track corresponding with gold utensil outer wall boss, the track lower extreme is equipped with the radial groove track, the orbital tip of radial groove is equipped with the constant head tank, gold utensil outer wall boss can be at the axial notch track, slide in radialgroove track and the constant head tank, the connecting hole bottom is equipped with the location spring, according to the electric pressure, the ambient temperature, changes such as temperature aremade up the insulator of installation at any time, the split changes insulator length, reach electrical safety, the standardized requirement of installation, the utility model discloses simple structure, convenient operation, labour saving and time saving.