Abstract: A novel weapon-target assignment model based on shooting probability constraint is proposed in which the impact of shooting probability on the effectiveness of air-defense operations is considered. The proposed model takes many factors into account，such as shooting probability，air strikes intensity，and fire transfer time of firepower unit. The proposed can give priority to using firepower units with quick response to intercept the targets with short flying time on the premise of meeting the thresholds of shooting probability and joint damage probability. At the same time，it minimizes the consumption of fire resources to provide continuous combat capability for the air-defense system.On this basis，an improved equilibrium optimizer algorithm based on nonlinear adaptive inertia weight is presented to solve the weapon-target assignment problem. The Tent chaotic map is used to generate the initial population to enhance the diversity of the population. And the inertia weight is introduced to balance local search and global search ability，which effectively improves the optimization ability of the algorithm. Simulated results verify the advantages of the proposed model and the effectiveness of the optimization algorithm.

Key words: air-defenseoperation, weapon-targetassignment, shootingprobability, firetransfertime, nonlinearadaptiveinertiaweight