Abstract: Analysis of node importance has been widely studied both at home and abroad, but not abundant in military field. The uppermost reason is that combat system is a complex giant system, and it is impossible to describe its node importance accurately by general methods, owing to its own complexity. This paper takes into account the characteristics of complex networks for combat systems, and abstracts the overall value of operational node combination, finally proposes a kind of node importance evaluation method based on function chain. Taking complex networks of combat systems as experimental objects, we compare and estimate the evaluation results of node importance respectively gained through function chain, node degree, PageRank and so on. The experiment results show that the node importance evaluation method based on function chain can e ectively evaluate each node importance in complex networks of combat systems and find the most important node.