The invention provides a nested high-reliability contact rotation system and a combined system and a method thereof. A single motion contacting body, multiple motion contacting bodies or multiple motion contacting bodies contacting one another as a whole is/are in contact with a first contacted body and a second contacted body under a force applied by a motion contacting body force applying mechanism. Motion contacting bodies like ball-shaped contacting bodies ensure that rotating bodies rotate relatively through gap-free contact, and make rotating bodies free of gap jump. The ball-shaped contacting bodies ensure that rotating bodies are not affected by relative rotation wear of the contact surfaces and are always in contact through motion following, ensure contact, and can be used for conducting. Multiple fulcrums can be obtained through multiple ball-shaped contacting bodies, so rotating bodies are aligned stably and rotate smoothly. Rotating bodies do not produce axial endplay under the condition of no radial run-out. Controlled movable contact can be easily realized.