The present invention discloses an insulation crossarm for live line work. The insulation crossarm for live line work is mounted at the top of a utility pole, and comprises a base rod, a telescopic rod, a guide rod, and movable slots. An upper end of the base rod is provided with a cavity corresponding to the telescopic rod. The telescopic rod is mounted in the cavity. The guide rod is transversely disposed on a side surface of a sleeve a. An open hole corresponding to the telescopic rod is disposed in the sleeve a in a vertical direction. The movable slots are mounted in the guide rod by means of transverse guide holes. The bottom of each movable slot is connected to a sleeve b by using a connecting rod. The connecting rod is movably connected to the movable slot and the sleeve b. According to the insulation crossarm disclosed by the present invention, a height of a device can be initially determined by adjusting the position of the telescopic rod in the base rod; a working height of the device can be determined by adjusting a height of the guide rod; and by adjusting a lateral position of each movable slot, the movable slot can be moved into a working position, and a conducting wire is mounted. Each movable slot can be moved by adjusting a position of the sleeve b and a length of the connecting rod, so that a hand is kept away from the conducting wire, and operation is safe.