The invention discloses a power supply line fault isolating method, device and system. The power supply line fault isolating method comprises the steps that voltage data of a power supply line are obtained; when the voltage data reach a preset value, a breaker body is controlled to be switched off; a communication module is controlled to send fault information to a preset terminal, wherein the fault information includes the fault type and the serial number of the breaker body. By the adoption of the power supply line fault isolating method, device and system, maintenance personnel can accurately learn about the specific position of the breaker body which is switched off after fault isolation, and thus convenience is brought to the maintenance personnel for line patrol and troubleshooting.