The safe operation of transmission lines is an important basis for ensuring stable transmission of electric energy, and the safety is greatly affected by meteorological factors. In order to evaluate and improve the risk early warning capability in the transmission system, this paper proposes a transmission line safety evaluation model that takes into account meteorological factors. Firstly, according to the characteristics of the transmission line architecture, an evaluation index system reflecting the operation status of the transmission line is constructed. At the same time, a new graph model weighting method is proposed based on the principle of graph theory to overcome the human subjectivity factor disadvantages in the weighting of the traditional matter?element extension model. Secondly, based on the matter?element extension theory, the comprehensive risk matter?element and safety rating of transmission lines are constructed, and the risk safety assessment and dynamic management model of transmission lines considering meteorological factors are established. Finally, taking a certain region as an example to study the operation risk of its transmission lines, the analysis results verify the scientificity and practicability of the transmission line safety assessment model.