In large aperture telescope optical system, Coude path is very important though it deliver the major optical path to enter in the Coude laboratory below telescope, coupling with the sub-optical system. Coude path is composed of many deflected mirrors, and position relationship among optical elements is important for its image quality. So it’s a key technique to ensure their accurate position relationships. On the basis of system requirement, a kind of tuning mechanisms is designed, including tip/tilt tuning mechanism utilizing semi-kinetic support, Dovetail-groove rail displacement mechanism and fine revolution structure. Each of them is characterized with long stroke and convenient operation. So they not only can assure the accurate position relationship, but also are suitable for adjustment and detect. The whole research technique can be a fine reference to the optic-mechanical system, and has been utilized in actual engineering.