Abstract: Because of the huge number and high relative speed, Near-Earth Objects pose a serious impact threat to the Earth. Early warning is an essential means to effectively deal with the threat, but the existing capacity is still not enough to fully protect the Earth from catastrophic impact. Since the occurrence of the Chelyabinsk incident in 2013, NEO defensive technology has become a hotspot in international research. China has now joined the SMPAG which is an international organization dedicated to the defense of near-Earth objects, but some specific research is still in its infancy. In this paper, the necessity and basic response process of developing NEO early warning and defense technology are expounded in detail. The international research progress of NEO surveys, international organization and its technical research, deep space exploration project and other aspects are expounded, and the orbital deflection defense is briefly analyzed. The basic strategy and the principles, advantages and disadvantages of five main defense techonolies are introduced, including nuclear explosion, kinetic impact, gravitational traction, changing solar light pressure and laser ablation. Then, it is concluded that the priorities for future work of NEO warning and defense are mainly:Improve searching and cataloging ability, enhance physical feature detection, promote defense technology research and carry out deflection test tasks. Finally, some development suggestions are proposed, including rapid improvement of monitoring and cataloging capabilities, promotion of basic research in various aspects, and actively participate in and carry out international exchanges and cooperation.