The Nanshan 1.2-m optical telescope is a reflector telescope with altazimuth mount and consists of two Nyquist focuses. The Nyquist focus for experiments on quantum communications has a focal length of greater than 13000mm and a field of view of no less than 1ʹˣ 1ʹ, and the other one for use in astronomical observations has a focal length of greater than 9400mm and an optical field of view of at least 20ʹˣ 20ʹ. At present, experiments on quantum communications are being undertaken by the telescope.