Abstract: Critical infrastructure has become a core research topic in the military field in recent years due to its significant role in national security. This study introduces a complex network improved analytic hierarchy process (CN-AHP), designed to assess the importance of different facilities within CI systems from two perspectives: system functionality and vulnerability to attack. The method consists of four key steps: 1) constructing a complex network model based on the spatial locations and element flow relationships within the infrastructure system; 2) analyzing functional weights of facilities in different functional sub-networks; 3) assessing concealment levels and damage difficulty of various facilities; and 4) analyzing the weights of sub-network functions and attack difficulty for different facilities, followed by a comprehensive importance assessment. An empirical case study was conducted to validate the method, demonstrating its feasibility. The calculation results ranked the facilities in this CI system by comprehensive importance in descending order as follows: Facility A, Facility C, Facility G, Facility D, Facility E, Facility F, and Facility B.