The invention relates to the technical field of power transmission line safety protection, and provides a power transmission line external damage prevention detection protection device and a use method thereof. The power transmission line external damage prevention detection protection device comprises a central processing unit, an alarm unit, a remote control unit, a communication unit, high-definition camera units which are respectively arranged at the left and right sides of a power transmission line, a moving object detection unit which is arranged below the power transmission line and candetect objects around the power transmission line, and a moving object deceleration unit which is arranged on the road below the power transmission line, wherein the moving object detection unit is connected with the central processing unit; the central processing unit is connected with the moving object deceleration unit, the alarm unit, the high-definition camera units and the communication unit; and the communication unit is connected with the remote control unit. According to the invention, all-weather monitoring is carried out on the power transmission line; external damage hidden dangerof the power transmission line is timely found and warned; the power transmission line damage prevention detection efficiency is improved; and a powerful guarantee is provided for improving the modern management level of the power transmission line in the power industry.