Long rod suspension type insulator has non-breakdown structure with balloon fitted outside. In recent years, this kind of insulator is applied of non-breakdown structure, deep creepage skirt and middle & big creepage distance structure. Normally rod type insulator is applied of lead antimony alloy to fix fitting. This kind of fixer is not expandable, which may not cause clay expansion damage and electric fault. There are fittings only on two ends of insulator, which reduces its weight greatly.