Large quantities of hexagonal boron nitride (h-BN) nanoplates with hexagonal morphologies have been successfully synthesized by a simple two-step route without using any template or catalyst, including combustion synthesis and then annealing processes. The phase content, morphology, and optical properties of the products have been characterized. It reveals that the obtained products are pure and of high crystallinity. The UVvis absorption spectrum indicates that the h-BN nanoplates have an optical band gap of 6.07 eV. Strong violetblue photoluminescence (PL) emission with a broad band ranging from 400 nm to 475 nm has been observed, indicating that the nanoplates as-grown by this simple route are promising for application in nanosize optical devices (LEDs, blue-light source, UV detector, etc.). The phonon lines features are obviously found in the PL spectra, the phonon frequency involved in these transitions is consistent with the BN E2g vibrational mode, which has been measured by the Raman spectroscopy.