Existing edge importance evaluation methods for a command information system (CIS) often neglect critical factors such as inter-node relationship strength, information propagation efficiency, and the high reliance of military operations on a command and control chain, limiting the accuracy and practicality of evaluation results. To address this, we first construct a structural model constrained by military tasks, refining the classifications and interaction rules of nodes and edges. By integrating OODA (observation, orientation, decision, action) loop closure logic, we define a command and control information value chain, overcoming the functional logic limitations of traditional topology analysis. Then, we design a comprehensive edge importance index (CEI) that integrates structure, function, and task by fusing local structural tightness, global information propagation efficiency, and task execution efficiency, and establish a dynamically weighted aggregation model. A case study illustrates the model’s superior accuracy in identifying critical edges. Furthermore, we propose a dual-dimensional evaluation strategy using network efficiency retention and a task-structure robustness index. Through simulation experiments, we compare the robustness and stability of different edge importance indexes under three CIS structures. Results show that the CEI outperforms others across all structures, effectively distinguishing functionally critical edges from structurally redundant ones, which verifies the validity and stability of the CEI as a comprehensive index, and provides a quantitative basis for CIS structural optimization and resilience design.