Sintering behavior and mechanism of barium titanate powders prepared by high-gravity reactive precipitation (HGRP) process has been investigated by a dilatometer. The mean particle size of barium titanate powders prepared by HGRP was about 80 nm. Pure BaTiO3 pellets were sintered at a constant heating rate of 2.0 K/min and the temperature of shrinkage-onset for pellet was 1060°C. The maximal shrinkage was 165um and the maximum of shrinkage rate was 8.0 x 10-3 / min at 1170°C. The sintering mechanism for the initial stages of sintering was determined by isothermal dilatometric measurements and was found to be viscous flow.