The accurate and efficient assessment of the transmission lines state is the key to carry out the intelligent maintenance. In this paper, based on a large collection of multiple period or full-time maintenance data of transmission line, the model of risk information entropy is established by using the risk assessment method to assess the transmission line state accurately, and the maintenance strategy for line unit is determined. After the state of the principle component is analyzed, the scores are calculated according to the proportion of main component and sorted correspondingly, and then the evaluation system with differentiation characteristics for the principle component state of transmission line is established to improve the efficiency of maintenance. The analytic hierarchy process, principal component analysis and risk information entropy are combined and the objective function of optimal weight with minimum deviation is adopted to determine the priority of the risk of each state and optimize the maintenance target. Through the application in the state maintenance of a 500 kV transmission line in a central province, it shows that the model is reasonable and feasible. This work is supported by National Key Research and Development Program of China (No. 2017YFB0902800) and Scientific and Technological Projects of Henan Province (No. 182102210258).