Namometer sized a-Si3N4particles of 10～nm in average diameter were obtainedby Laser Induced Chemical Vapor Deposition (LICVD). The spectra of UV absorption andfluorescence of a-Si3N4 particles in different colloids weremeasured. Six fluorescent peaks from 3.0eV to 4.1eV were found for the first time. According to the absorption andfluorescence spectra of the particles, we studied their energy level structure. We alsodemonstrated that silicon dangling bond ≡Si0 plays a dominant role in the spectrum character fornanometer a-Si3N4 particles.