Abstract: The implementation of software-defined network and network function virtualization (NFV) in power communication systems provides a new solution to the issue of cross-space cascading failures in the scenario of cyber-physical system. Aiming at the remedial control services in the OTN layer, we propose a routing strategy for service function chains based on NFV technology to reduce the risk of power system failures evolving into cascading failures due to the disruption of remedial control services. First, a cascading failure index is introduced to quantify the significance of various types of information within the same class of communication services. On this basis, the traditional risk balance strategy is improved, and the obtained risk weight is introduced into the routing strategy. The core model is constructed as a two-stage robust optimization problem and is solved using the column-and-constraint generation (C-CG) algorithm. The superiority of the proposed routing strategy is verified in the IEEE 30-bus system through a comparison with the shortest path routing algorithm commonly used in practical operations. The results demonstrate that the routing strategy effectively enhances the robustness of information transmission, alleviates the concentration of high-importance information in localized network segments, and mitigates the potential for communication faults to trigger cascading failures in the power system through adjustments on the cyber side.