To solve the problem of air defense system modeling and assessing which is partial to determine the nature, only paying attention to system structure and overlooking entity and relation property in system, some efforts have to be done. On the basis of recent model and assess method, put forward air defense system model based on adjacency matrix, define capacity assess vector, use the target value evaluation method that was based on target contribution degree to system capacity and put forward target rank and discrete degree based on Pareto dominance and crowding distance so as to form Non-inferiority rank algorithm, and use the weighting and cost performance and other network access methods as the comparison, establish random examples for simulation, simulation result proves that the air defense system model based on Markov logic and Non-inferiority value rank algorithm are efficiency.