Abstract: The interference effect of airborne towed decoys on tracking radar and missile seeker is proved to be very effective,and the towed decoys make grave influence to the operational efficiency of weapon systems.The operation mode and the principle design of towed decoys are analysed,the condition of the radar separated from towed decoys is proposed,and the method which includes radar method and photoelectricity detection method to counter the towed decoy is presented.This paper also discusses not only the operational mode of command guidance systems,but also the operational mode on missile seeker.