ZnO micro-hexagons with controllable morphologies were synthesized with the assist of benzenedicarboxylic acid (BDC) from zinc hydroxide nanostrands at 120 °C. With increasing the concentration of BDC, the structures evolved from hexagonal disks to hexagonal pyramids and eventually to coarse hexagonal pyramid flakes. The reason was that the growth along the c axis was preferentially suppressed at relatively low BDC concentration, while at higher concentration, the BDC could uniformly adsorbed on the whole surface. The photoluminescence properties of the obtained ZnO hexagons were also investigated at room and low temperature. The ZnO hexagonal disks with lowest defect showed the best optical performance.