Aiming at the problem of the target threat assessment of the aerospace defense operation command, the method that combination weighting with Particle Swarm Optimization(PSO)for the aerospace threat assessment base on intuitionistic fuzzy is proposed, in the case of the uncertain information of aerospace target assessment indexes being interval quantified, and the weights of the indexes being unknown. In this method, the weights of the indexes are obtained in the way that optimize the function of subjective and objective weights by PSO base on considering the index preference of the decision makers and the objective optimization rank synthetically. Then the multi-attribute intuitionistic fuzzy threat assessment model is constructed. Finally, the effectiveness of the proposed method is verified by an example of aerospace target threat assessment.