The uniformity particle size distribution (PSD) and coarse particle size of alumina were synthesized by precipitating aluminum ammonium sulfate solution with ammonia. The effect of temperature and ammonia concentration on precipitation products was studied by using X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), laser particle size analyze and fourier transform infrared (FTIR) spectroscopy. The results show that the particle size distribution of the precipitations is greatly affected by temperature and ammonia concentration. The precipitation product belongs to boehmite and its particle size has little variation after calcining. The optimal precipitation condition is 7.0 mol L-1 ammonia at 90 degrees C. Under the optimal precipitation condition, the D10, D50, and D90 of the precipitation particles are 12.54 mu m, 41.28 mu m, and 78.19 mu m, respectively. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.