This article studies a method of eliminating the false localization of multiple targets on the basis of air based double flat roof, and gives a passive localization method based on min-angle threshold judgment. In this method first the "least distance method" cross-localization algorithm is used to work out the estimation value of the target position, and work out the pitch angle of the value compared with the value of main scout. Then, the D-value between the foregoing value and measured pitch value of main scout is worked out. Finally, by comparing the certain threshold with the D-value, the false dot which exceeds the threshold is eliminated. The result of simulation shows that using the method can enhance the correct probabilities of data association and reduce the calculation times which can meet the need of project.