Anti-torpedo can be divided into active and passive. At present, destroyer anti-torpedo mainly includes jammer, air curtain bomb, acoustic bait and even sound absorption and noise reduction. The scheme of towing lightning protection and towing the back cabin of the ship can be used to defend the wake torpedo. A multi-top trawl made of high-strength fiber is placed in the cabin, which is strong enough to catch torpedoes or add explosives to the net. The tail wing of the towing module is equipped with a transducer, which can actively or passively detect torpedoes. There are various sensors in the engine room. After the towing ship telemetry, the depth and position of the towing cabin can be controlled by steering to stop the torpedo. Anti-torpedo rocket depth charge is also a modern anti-torpedo means. This kind of deep bomb can be suspended at a predetermined depth through the collar airbag, and a transducer is arranged around the warhead to detect the echo of the incoming torpedo, which will detonate when the torpedo passes the nearest point. The microcomputer and acoustic fuze equipment on the missile can also be used to generate a decoy signal for the acoustic homing torpedo to guide the torpedo to detonate nearby. This scheme has been applied in the anti-torpedo operation of surface ships. For example, the RBU 12000 rocket depth charge launcher was installed on the Russian aircraft carrier in service in 1990, and it was reported that it was used to intercept torpedoes. In addition, in the anti-torpedo system of French slat surface ship, the countermeasure equipment is also launched into the water by "Sage" rocket launcher. In this way, the bait can be quickly dropped in different directions and distances, which is beneficial to distract the attention of the incoming torpedo. In fact, in addition to anti-torpedo torpedo, the most practical way of self-protection at present is to cheat. After all, the technical difficulty of torpedo to torpedo is comparable to that of land anti-missile, and the technology is not particularly mature.