The effect of Ba/Ti ratio on crystal structure and microstructure was studied using XRF, Raman spectra, XRD, SEM, and TEM. A series of BaTiO 3 powders were synthesized from high purity BaCO3 and TiO2 powders with Ba/Ti ratio ranging from 0.92 to 1.08 at 1200°C calcination temperature for 4 h. The XRF results confirm the Ba/Ti ratio of these synthesized BaTiO3 powders is ranging from 0.98 to 1.02. The Raman spectra demonstrate that the BaTiO3 powders are tetragonal phase and without second phase. The XRD data show a significant change in tetragonality (c/a ratio) with Ba/Ti ratio from 0.99̃0.98. The Ti-excess samples exhibit a higher tetragonality (c/a ratio = 1.0109) than that in Ba-excess samples (c/a ratio = 1.0097).