Abstract: The existing state assessment method of transmission lines is relatively simple, and does not consider the influence of operating years and maintenance interval on transmission lines state assessment.To solve above problems, a state assessment method of transmission lines based on proportional hazard model is proposed.Firstly, the key parameter system of the transmission lines state assessment is established, and the key quantity of transmission lines state assessment is obtained.Then a proportional hazard model is used to score the status of each transmission line unit.Finally, the weight of each unit state quantity is obtained by the analytic hierarchy process.According to the comprehensive state assessment, the dynamic evaluation of transmission lines and the rapid detection of abnormal state are realized.Through an example analysis of the line state assessment, the feasibility of the method in this paper is verified, and an assessment model considering time characteristics is proposed, which has certain practicability and reference value.