Characteristics of the plume plasma produced by UV (λ=308 nm) laser ablation of a hot-pressed hexaganol boron nitride (h-BN) target have been investigated in a high vacuum at a laser power density ranging from 0.1 to 3.2×108 W/cm2. Time-resolved detection of the ablated species has been achieved by using a quadrupole mass spectrometer and an ion probe. The average kinetic energy of ablated B+ is much larger than that of B, and increases with an increase in the laser power density, whereas the acceleration of neutral B is limited. The ionization degree in the plasma varies from 0.1 to 15% with increasing laser power density. The angular distributions of the ion flux and the total particle flux can be fitted by a cosine or a bicosine function and strongly depend on the laser power density.