Abstract: Abstract: With the development of electric power system protection technology, the scope and area of services needs for power system protection are gradually expanding, and it needs the support of a safe and reliable communication network with convenient deployment. Currently SDH (Synchronous Digital Hierarchy) is an important basic communication network for power system wide area protection and distribution network protection to transmit and exchange information. This paper briefly describes the principle of SDH-based control plane technology ASON (Automatically Switched Optical Network), and introduces the performance constraints of protection transmission links and routing control test cases according to the special application requirements of power system. Based on the test results of performance and functions of different manufacturers' ASON system, this paper presents the prospect of access mode, potential risks and application trends of ASON technology based on SDH in power system. 1. Introduction Introduce the development of current protection services in electric power system, and the requirement for communication network. Wide area information based protection and control system is not only a multi-professional data exchange information carrier, but also a protection and control functions implement carrier. 2. ASON technology brief 2.1 principle of SDH-based control plan technology Describe the technical advantage of SDH-based ASON system and its brief technique principle of control plane. ASON is a kind of flexible, highly scalable optical network that provides on-demand service directly at the optical layer. SDH equipment as a kind of transmission carrier of ASON usually provides linear or ring network structure, and the introduction of ASON control plane makes transmission, exchange and data network combine to realize the true routing setting, end-to-end service scheduling and network Automatic recovery. 2.2 service classification and performance assurance Describe protection service classification and relative performance level. Describe differences between soft permanent connection and permanent connection. 2.3 special functional requirements in electric power system According to the development of wide area protection and distribution network protection, introduce the relative special ASON function and performance adapt to the application in electric power system. 3. Performance and functions test case 3.1 routing constraint rules Describe routing constraint rules based on link cost, include/exclude resources, and the number of nodes etc. 3.2 performance test case (1) Routing protocol convergence time test; (2) control plane protection recovery time test 3.3 functional test case (1) 2M SPC preset routing recovery test; (2) 2M SPC break down first and establish up later function test 4. Application analysis of electric ASON Analysis the test result above, give the prospect of access mode, potential risks and application trends of ASON technology based on SDH in power system. 5. Conclusion This article could be a reference to the communication network plan for wide area protection and distribution network protection.