The jamming effectiveness of the towed decoy of the subsonic target flying at super low altitude in the test against the air defense missile with different guidance system is analyzed. Firstly, the jamming effectiveness of the towed decoy on the shipboard radar is analyzed on the basis of reasonable assumptions of the length of the towing cable and the route shortcut. And then, the process and the effectiveness of the towed decoy against air defense missile weapon with radar and infrared guidance system are analyzed. At last, based on typical trajectory simulation example, the guidance process of the missile is analyzed quantitatively and the views about the use of the towed decoy in test are proposed.