Particulate samples (>0.45 μm) from a hydrothermal plume in Lau Basin are collected by filtering on deck and analyzed by scanning electron microscope (SEM) and X-ray energy dispersive spectroscopy (EDS). Four types of particles have been morphologically characterized. So many particles related to hydrothermal activity and the distributions of amorphous particles in different water layers indicate that the study station locats at the incipient stage of formation of hydrothermal plumes, and during the several hundreds meters there may exist an active hydrothermal vent area.