In this letter, optical microcavities are deposited directly on mesa-patterned substrates, and three dimensional Bragg cavities are formed due to the conformal deposition process. The room temperature photoluminescence spectra of three-dimensional Bragg microcavity exhibit a series of discrete resonant peaks. Optical field profiles of corresponding resonant peaks were given, by finite difference time domain simulation. These discrete peaks obviously show cavity resonant characteristics and optical field is mostly localized in the cavity layer. Also size dependence of cavity modes was concluded from our experimental results. (C) 2010 Elsevier B.V. All rights reserved.