Abstract: With the increasing demand of smart grid for the reliability of power communication networks, the protection of stations in power communication networks is becoming more and more mature, but the protection of links cannot be fully implemented due to the huge cost. In order to solve this problem, we propose a critical link identification algorithm considering main and standby routing. First, this algorithm calculates route available rate by the available rates of the links making up the route. Then the transporting probability of the traffic in this route based on the route available rate is calculated. Finally, we calculate the mathematical expectation of the traffic importance carried in a link in two conditions, main route and standby route, to obtain the importance of this link, and identify critical links by link importance. The simulation results show that the algorithm fully considers the actual situation that the design of the power communication network meets the N–1 requirement, and the single link failure cannot directly lead to business interruption, and the identification of key links is more accurate and has application value.