Abstract. Efficient enhancement of photoluminescence from Er/O-doped silicon (Si) on silicon-on-insulator (SOI) wafer in two-dimensional (2D) airbridge symmetric slab hexagonal photonic crystal (PC) gradient double-heterostructure microcavity has been demonstrated at room temperature. A single sharp resonant peak with 1541.7nm communication wavelength dominates the photoluminescence (PL) spectrum and significant PL enhancement is obtained compared to the case of identically implanted SOI wafer at pumping power of 15mW. The obvious red-shift and degraded Q-factor of resonant peak are present with the pumping power increasing, and the maximum measured Q-factor of 6284 has been achieved at pumping power of 1.5mW.