A optimal path selecting method based on security is proposed for relay protection services of optical-fiber circuitous channel. Firstly, the requirements and types of optical-fiber relay protection channels are described, and the necessity of configuring the optimal path is analyzed from the security perspective. Secondly, an improved Dijkstra algorithm is used to select paths, considering the security measure of nodes and links. For links security balancing, a function is used to adjust the weights of the links. Finally, examples verify the feasibility and effectiveness of the new algorithm.