The 100m-baseline optical interferometer in China is now under construction. It consists of three 600mm telescopes and  forms a maximum baseline of 100 meter. The three telescopes are placed in domes with an auxiliary room used for the  adaptive optics and the dual field  optics. The central optical room are used to place the delay lines and the beam  combiners . The dome and the central optical room are connected by vacuum pipeline.  It is hoped to compensate the opd  with a residual of 100nm @ H band. The goal of imaging resolution is about 1.7mas when observation in H band.The  main science goals of the telescope array are to achieve high precision astrometry, and to image the bright stars with high  resolution.