The invention discloses equipment having live line water washing and deicing operation functions for a power transmission system and an application method of the equipment. The equipment comprises a crawler chassis, a rotary support, a horizontal rotary table, an insulation operation arm and a washing device; the horizontal rotary table is fixed to the crawler chassis through the rotary support; the insulation operation arm comprises an insulation large arm and an insulation small arm that are hinged mutually; one side of the horizontal rotary table is connected with a rotary disc arranged in the vertical direction; the outer side of the rotary disc is connected with a mounting seat; a large arm driving gear motor and a small arm driving gear motor are arranged on the mounting seat; the lower end of the insulation large arm is hinged to an output shaft of the large arm driving gear motor; the insulation small arm is hinged to an output shaft of the small arm driving motor through a drag link mechanism; a rotary disc driving device is arranged on the horizontal rotary table; and the washing device is connected with the upper end of the insulation operation arm and carries out close range washing on insulators. The horizontal rotary table, the rotary disc and the two driving gear motors are matched for use, so that the equipment has the advantages of position adjustment accuracy, high cleaning efficiency, a good cleaning effect and low water consumption.