The invention provides a method for replacing a V-shaped part of a Y-type insulator of a power transmission line tower. The method comprises the steps of mounting a transmission system on a cross arm of the power transmission line tower; transporting a lifting tool by utilizing the transmission system; mounting one end of the lifting tool on the cross arm and mounting the other end of the lifting tool at the junction of a V-shaped part and an I-shaped part of a Y-shaped insulator string; upwards lifting the I-shaped part of the Y-shaped insulator string by using the lifting tool; removing a damaged insulator string in the V-shaped part of the Y-shaped insulator string, and transporting the removed insulator string to the ground through the transmission system; and transporting and mounting a new insulator string. The method provided by the invention is wide in application range, easy to realize and high in operability, can replace the V-shaped insulator in a charged condition, and ensures the stability and economy of a power transmission line.