To solve the problem that it is difficult to manually inspect the safety of the operators during the process of high voltage live working

a method for inspecting and warning based on time of flight（ToF） camera is proposed. Based on the analysis of methods and typical working situations of live working on high voltage transmission lines

the safety working space of the operators is divided based on the minimum approach distance. The real time safety inspection is implemented with the use of ToF depth camera. The examination of crossing boundary of the safety working space and invasion are used to implement the safety warning. Meanwhile

the insulating ropes which influence the safety inspection are identified and excluded

which improve the accuracy and applicability of the proposed method in the complex field environment. In the field test

an observer on the tower and the system simultaneously implement the safety monitoring. The system has twelve alarms

while the observer has only five alarms. The other seven alarms are due to the fact that the foot of the operator only touched the edge of the alarm line

which requires high accuracy

so the observer failed to alarm in time. The accuracy and reliability of the proposed system of live working safety inspection for high voltage transmission lines based on ToF camera are verified by field tests. By contrast with the manual inspection

the system can improve validity of safety inspection and prevent the occurrence of casualties.