Dense nanocrystalline BaTiO3 ceramics with a homogeneous grain size of 30 nm was obtained by pressure assistedsintering. The ferroelectric behaviour of the ceramics was characterized by the dielectric peak at around 120 ℃, the P-Ehysteresis loop and some ferroelectric domains. These experimental results indicate that the critical grain size for thedisappearance of ferroelectricity in nanocrystalline BaTiO3 ceramics fabricated by pressure assisted sintering is below 30 nm. The ferroelectric property decreasing with decreasing grain size can be explained by the lowered tetragonality and the ’dilution’ effect of grain boundaries.