In view of the problem that deficiencies exist in current air target threat assessment methods, an air target threat assessment model based on regret theory and multi-criteria is proposed. Firstly, an assessment index system is constructed by individual threat, individual value and threat urgency, and the entropy weight method is improved by introducing Pearson's correlation index to get the objective weights of the indexes. And then, a threat assessment model based on the three-way decision methods improved by the regret theory is established. Finally, a multi-player game model is constructed based on the different assessment criteria, and the Nash equilibrium is solved to get the target's threat categorization and ordering results. The simulation results show that the proposed method enables commanders to obtain the customized classification and the threat ranking results according to their decision-making preference, and the method is valid.