It only took more than six years from the discovery of nuclear fission in 1938 to the manufacture of the atomic bomb in 1945. Since 1945, the atomic bomb technology has been continuously developed, the volume and weight have been significantly reduced, and the tactical and technical performance has been improved day by day. The W33M422 nuclear bomb used in American 203mm gun weighs1/kloc-0 ~120kg, with a diameter of 203mm and a length of 940mm, but its power is still about10000t TNT equivalent. The miniaturization of atomic bomb is of great significance to improve the tactical and technical performance of weapons and to be used as a "trigger" in hydrogen bombs. In improving the performance of atomic bombs, an explosion-assisted atomic bomb has been developed, that is, thermonuclear materials are added to the atomic bomb to fission more nuclear charges, thus increasing the power and improving the utilization rate of fission charges. In terms of power, in order to meet the needs of battlefield use, a variety of nuclear weapons with low power (kiloton,100t,10t TNT equivalent) and adjustable power have been developed. For example, the American special nuclear mine code W54/M 129 has adjustable power, ranging from 10 to 103 tons of TNT equivalent, and the nuclear warhead weighs only 26.6 kilograms. The initiation mode of high-energy explosives and the structure of nuclear devices are constantly improving. On the one hand, improve the utilization rate of high explosive and the compression of nuclear charge, so as to increase the power of nuclear explosion and save nuclear charge; On the other hand, it improves the penetration ability, survivability and reliability of nuclear devices. In order to improve the safety performance of atomic bombs, sensitive high explosives in nuclear devices are gradually replaced by insensitive high explosives. This kind of insensitive high-energy explosive is not easy to detonate even in accidents such as shotgun shooting or plane crash, thus preventing pollution caused by accidental nuclear explosion and the scattering of radioactive and chemical toxic substances such as plutonium.