The utility model relates to a double-string insulator insulating tractor for adjusting the looseness of a 66-kilovolt transmission line in a hot-line mode or replacing all fittings and power-off elastic wires at head portions of insulators. The tractor comprises a pull plate, a connecting piece and two hanging plates connected to the connecting piece. The connecting piece is of a structure which is formed by connecting an upper regular-triangle-shaped connecting plate with a lower regular-triangle-shaped connecting plate through one shaft and bolts at three corners and is provided with a middle gap. One end of the pull plate is movably connected with a shaft on the connecting piece. The two hanging plates are movably connected with the other two shafts on the connecting piece. The power-off work can be converted into the hot-line operation, and therefore the power supply amount and reliability are improved; workers are protected against harms caused by faradism to the maximum extent, and safety is improved; due to the power-off work, the workers are prevented from climbing out for installation, and the physical power consumption of the workers is lowered; due to the power-off work, the work time is saved, and the work completion rate is increased; during work of a special-shaped rod tower and a seriously-downwards-inclining elastic cord, operation is more convenient.