High purity, submicron BaTiO3 powder was prepared by a hydrothermal technique using Ba(OH)2.8H2O, TiCl4 and NH4OH as starting raw materials. The submicron BaTiO3 powder was synthesized at 130~23$0^{circ}C$ for 2.5h to yield highly crystalline particles with a narrow particle distribution. The mole ratio of Ba(OH)2.8H2O/TiO(OH)2 was 1.5. It is possible to obtain BaTiO3 with Ba : Ti=1.00$pm$0/01. The samples densified well at 13$25^{circ}C$, showing a uniform and fine grain structure. The grain size ranged between 0.3 and 0.5${mu}{ extrm}{m}$. The products obtained by hydrothermal treatment at various temperatures from 130 to 23$0^{circ}C$ were characterized by XRD, DTA, BET and SEM etc.