The invention provides a method for disconnecting a lead by a live-line work robot. Based on a main mechanical arm, an auxiliary mechanical arm and a camera used for collecting image data of a workingscene on a robot platform, the mechanical arms are controlled through a control room to complete the following work: the auxiliary mechanical arm clamps the lead; the main mechanical arm firmly grasps a wire clamp, a pneumatic wrench at the tail end of the main mechanical arm aligns to a nut on the wire clamp and unscrews the nut; the auxiliary mechanical arm clamps the lead, enables the lead tobreak away from the wire clamp and then clamps the lead to be away from the working area; and the main mechanical arm enables the wire clamp to break away from a wire and places the wire clamp in a toolbox. According to the invention, the lead supported and connected to the wire is disassembled through the mechanical arms of the live-line work robot under the condition that the power is not interrupted, so that negative effects brought about by power interruption are avoided, and the reliability of power supply is improved.