Not long ago, the upgraded version of the M1E3 Abrams tank in the equipment update plan released by the US Army attracted attention. It can resist attacks from new top up ammunition and has significantly improved protection capabilities compared to its predecessor. Almost simultaneously, the anti kinetic energy bomb capability of the German Leopard 2A8 main battle tank was improved to the level of 800mm homogeneous steel. The upgrading of the protective capabilities of these equipment is closely related to the use of advanced composite armor. Composite armor is a new type of armor that is composed of two or more different materials and can effectively resist attacks from armor piercing and piercing shells. As the "Golden Bell Shield" of armored vehicles, its birth originated from the "Armor Bullet Competition". After World War II, the power of anti tank missiles significantly increased. If only relying on thickened shell steel plates to enhance protection capabilities, armored vehicles will become very heavy and their maneuverability will significantly decrease. In the 1960s, the Soviet Union began to develop a three-layer composite armor consisting of "steel+fiberglass+steel" to enhance the protection of the T-64 tank. With only a weight increase of 4 tons, the armor piercing ability was increased to the level of 600mm homogeneous steel, which was equivalent to putting a "lightweight anti tank suit" on the tank. From then on, composite armor stepped onto the historical stage. After more than half a century of development, composite armor has undergone significant changes in materials, structure, intelligence, and other aspects. The materials used are constantly updated. Ceramics are the core components of composite armor, and over the years, their types have become increasingly diverse and their applications have become more widespread. In 1962, the United States was the first to combine alumina ceramics with aluminum alloys for helicopter protection, pioneering the application of ceramics in composite armor. Nowadays, new types of alumina ceramics have significantly improved their toughness and resistance to multiple impacts while maintaining hardness through improved sintering processes. The "Jobam" armor of the British "Challenger 2" tank uses silicon carbide ceramic modules, combined with a steel backplate, which can continuously resist attacks from multiple RPG rockets or one anti tank missile, improving its protection capability. Further optimization of internal and external structures. The modular concept is now widely used in composite armor. The gap type composite armor of the German "Leopard" 2A7 tank is fixed with additional modules by bolts, with equivalent protection reaching the level of 600mm homogeneous steel. This structure is convenient for the use of armor and can effectively shorten the battlefield repair time. The modular composite armor used in the French Leclerc tank has a more scientific connection method between modules, and the internal structure of the modules is also innovative. By arranging and combining different materials, the defense effect against different ammunition is improved. In addition, some countries are exploring the application of new structures such as honeycomb and grid in composite armor, in order to better absorb explosive energy and resist impact through structural deformation. Pay more attention to combining with other defense methods. Currently, combining active defense systems with composite armor to enhance tank protection capabilities has become a choice for many countries. The radar in the active defense system can quickly detect incoming targets, calculate the optimal interception position, and then launch interception missiles to destroy them. The "fish that escaped the net" is "resisted" by composite armor, thus forming a dual protection. Moreover, countries are actively researching and attempting to use artificial intelligence algorithms to enable active defense systems and composite armor to automatically adjust defense strategies based on the characteristics of incoming targets, achieving intelligent protection. Currently, the development of composite armor also faces multiple challenges. For example, the protective capability of composite armor relies on the combination and synergy of metal, ceramic, and polymer materials, but the physical properties between materials make this synergy and fusion more difficult; Composite armor will use a large amount of high-performance materials, which are expensive in cost; The emergence of new opponents such as serial armor piercing shells has forced a new round of improvement in the performance of composite armor. Of course, future armored vehicles may break through the scope of traditional physical protection and build comprehensive protection barriers in the multidimensional battlefield of electromagnetic spectrum, information space, and physical defense. At that time, these challenges may no longer be a problem. (New Society)