Abstract: To address the practical problem of electric shock caused by workers mistakenly climbing energized towers or the energized side during outage maintenance of high voltage transmission lines, this paper designs an electronic identification marker for transmission lines. The marker can automatically issue a tower climbing prompt when workers enter the designated tower climbing area. The device consists of seven parts: a display unit, a positioning unit, a control unit, a prompt unit, a communication unit, a power supply unit, and a fixing unit. Considering the requirements of reliability, portability, and safety, this paper designs and selects each part and conducts a series of experiments for verification. Field test results show that the device can correctly issue a tower climbing prompt when workers enter the area within 2 m of the target tower leg, without false alarms, thereby effectively ensuring the operational safety of construction personnel.