Abstract: At present, the inspection of transmission lines carried by helicopters with special equipment is one of the important means to find the defects of transmission lines and ensure the safe and stable operation of transmission lines. However, with the increase of the operating mileage of UHV lines, there are greater differences in the operating environment and topographic conditions of the lines. The original way of operating according to the whole line does not meet the differentiated inspection requirements of helicopter inspection operations. How to give full play to the technical advantages of helicopter inspection and carry out helicopter transmission line inspection is one of the development directions of transmission line inspection management in the future. Considering the historical defects of line inspection, terrain, operating conditions, user evaluation and other factors, this paper proposes an evaluation method of transmission line operating conditions. This method evaluates the operating conditions of transmission lines by quantifying various evaluation indicators, and supports helicopters to carry out differentiated inspection work. Through the scoring analysis of a 500kV Line in North China, it is concluded that this method can effectively carry out hierarchical evaluation of transmission lines and support differentiated helicopter inspection of transmission lines.