Abstract: Kinetic impact is regarded as the most technically feasible method for asteroid defense. Conducting an on-orbit demonstration and verification mission would not only enhance the technological maturity of kinetic-impact deflection, but also reveal the orbital deflection behavior of near-Earth asteroids, thereby providing decision-making support for future responses to real near-Earth asteroid impact threats. The orbital dynamical characteristics and structural, physical, and chemical properties of near-Earth asteroids are critical to the successful implementation of kinetic-impact missions. At the same time, such missions would provide an unprecedented opportunity to investigate the internal structure, composition, and mechanical properties of near-Earth asteroids. In addition, kinetic impact would serve as a unique “natural experiment,” offering a key case study for impact physics from the perspective of comparative planetology and thereby promoting the coordinated development of planetary science and planetary defense technologies. Focusing on China’s first asteroid defense demonstration and verification mission planned before 2030, this paper systematically reviews the frontier scientific questions in kinetic-impact asteroid defense, with the aim of providing a reference for mission design, implementation, and preliminary scientific research.