Metal organic frameworks Co1Cu2(BHTC)2 was prepared from biphenyl3,4',5tricarboxylate as organic ligand with hydrothermal method, and then characterized by XRD, SEM, TEM, TGA and FT-IR technology. The effect of temperature and crystallization time on the crystal growth and the growth mechanism of Co1Cu2(BHTC)2 was studied by SEM method. This work provides a new way of the crystal growth of nanoporous material. The results indicate that the crystal morphology changes markedly with the increase of crystallized time. The small hexagonal secondary building units (SBUs) were assembled by sharing the same prism of the tiny crystals, and then aggregated into a bulk hexagonal plate-like crystal.