$BaTiO_3$ fine powder was synthesized by hydrothermal process from the mixture of titania-hydroxide($TiO_2{cdot}xH_2O$) and barium hexa-hydroxide ($Ba(OH)_2{cdot}8H_2O$) as starting materials. Fine powder(< 100 nm) was made under the reaction conditions of 18$0^{circ}C$,10 atm, 1.5 hr in autoclave and showed cubic structure. The powders were sintered by a spark plasma sintering technique from 1050~115$0^{circ}C$ for 5 min. The grains of sample sintered at 110$0^{circ}C$ were about 0.9${mu}m$ in average size and showed the mixture of cubic and tetragonal structures.