<p>The degree of traffic electrification is increasing daily, and there is an obvious coupling feature between traffic networks and power networks. To address the random influence of electric vehicles in a traffic network on the line importance of a power network, a line importance analysis method for a traffic–grid coupling network is proposed. First, a traffic–grid coupling network model is established. Next, a model for the charge and discharge behavior of electric vehicles is developed utilizing the Monte Carlo method along with a Markov chain. Furthermore, an evaluation system for the significance of traffic-grid coupling network lines is created, taking into account how electric vehicles affect the importance of power network lines within the traffic network. Finally, for each evaluation index, an index weight distribution scheme under an analytic hierarchy process–hesitation fuzzy decision is proposed. Analysis of cases demonstrates that the proposed approach can assess the significance of lines within the traffic–grid coupling network. It also confirms that implementing specific charging and discharging regulations for electric vehicles can significantly mitigate the random effects of their integration on the importance of power network lines.The research results have certain guiding significance for the stable operation and intelligent construction of power networks.</p>