In order to improve the association accuracy between radar target and IFF plot in complex environment， a method based on gray theory is proposed. In different scenarios， it can be judge whether there is competition among multiple radar targets when it is associated with IFF plot by calculating the gray correlation degree. If there is， the historical information of association between radar target and IFF is used to modify the gray correlation degree. Finally， the associated decision is completed based on the recognition of maximum gray correlation degree to form the identification of the target’s friend and foe attributes and the identification confidence estimation. Simulation results in typical scenarios show that， through multiple interrogations and association with the target， it can improve the association accuracy in different environment and the confidence degree of cooperative target attribute determination.