In this paper different shapes of ZnO crystals were synthesized by hydrotherma l method when different concentrations of mineralizer were used. When KOH was le ss than 2mol·L-1 and the fill factor was approximately 35%at 350℃, ZnO cryst als were synthesized with size of several hundred nanometer or several micron. T he shapes of crystals were hexagonal cones. When 3mol·L-1 KOH was used as mine ralize at 350℃and the fill factor was approximately 35%, the crystals with man y different sizes were synthesized, the size of maximal crystal was over 100 mic ron, the small-size crystals were only several micron. When mineralizer KOH was less than 1mol·L-1 and the fill factor was approximately 35%at 430℃, ZnO cr ystals were synthesized with size of several hundred nanometer or several micron . The shapes of crystals were hexagonal cones. When 1.5mol·L-1 KOH or 2mol·L -1 KOH was used as mineralize at 430℃and the fill factor was approximately 35 %, the high quality and hexagonal prism crystals were synthesized with many dif ferent sizes, the size of maximal crystal was over 100 micron, the small-size c rystal was only several micron. Especially when 3mol·L-1 KOH was used as miner alize at 430℃and the fill factor was approximately 35%, the high quality and h exagonal prism crystals were synthesized with size of 1mm along c axis. The exposed faces were hexagonal faces m{}, hexagonal cone faces p{}, negative pola r faces O{}. In addition, many crystals with the shape of hexagonal cone and in several micron to 50 μm of size were present. The exposed faces were hexagonal cone faces p{}, negative polar faces {}.
