Abstract: Most small bodies in the solar system have low orbital inclinations, concentrated near the ecliptic plane. However, some small bodies exhibit high orbital inclinations (i > 20°) and are referred to as high-inclination small bodies. The discovery and study of these high-inclination objects are reshaping traditional understanding and challenging classical dynamical models. With the advancement of wide-field sky survey projects, an increasing number of small bodies with high-inclination and even retrograde orbits have been observed. Their unique orbital configurations suggest complex formation mechanisms and evolutionary histories. High-inclination small bodies differ significantly from ecliptic plane objects in terms of surface composition, size distribution, and dynamical behavior. Their formation mechanisms involve various pathways, such as gravitational perturbations and planetary scattering, resonance capture and inclination excitation, and the influence of potential Planet Nine. These objects not only serve as "fossil records" of the early evolution of the solar system but also provide new research perspectives for planetary formation theories, interstellar material exchange, and deep-space resource exploration.