A series of disk-rod-disk liquid crystal trimers have been synthesized. Two triphenylene discogens have been connected to a biphenyl mesogen via CuI-NEt3 catalyzed alkyne azide cycloaddition in toluene at room temperature. The trimers have been characterized by using 1H NMR, IR, high resolution Mass spectra and the mesomorphic properties investigated with polarized optical microscopy (POM), differential scanning calorimetry (DSC), and X-ray diffraction. The result shows that the trimers exhibited rectangular columnar mesophase (Colr). The length of the flexible spacer connecting the three segments has important influence on the thermal behaviors of the trimers.