This telescope has 30m aperture, segmented primary mirror and alt-azimuth mounting. The aspherical primary mirror with f-ratio 1.2 consists of 1122 partial annular submirrors. The optical system includes Nasmyth I and II systems,Cassegrain system, coude system and a wide field of view system. There are four Nasmyth platforms. Two Nasmyth I foci are located on the upper floor and two Nasmyth II foci are located in the lower floor. All Nasmyth I, II and Cassegrain systems use same one secondary mirror, and all are R-C systems. With adaptive optics system, several diffraction-limited observations can be operated simultaneously on Nasmyth II platforms. The wide field of view system has 20 arcmin FOV, can correct atmospheric dispersion and the low space frequency error from primary mirror and atmosphere turbulence. A special rocking chair structure is designed which can realize the horizontal axis on the front of primary mirror. The tolerances of the surface shape and position of submirrors are given. The issues about tip-tilt correction and adaptive optics are discussed. Some formulae on rotating conic surface especially used for segmented mirror are given.