Green microcavity organic light-emitting diodes (OLEDs) are fabricated by using double metallic mir-rors in microcavity structures and double light-emitting structures. The structure of the device consists of Al(15 nm)/MoO3(4 nm)/2T-NATA(10 nm)/NPB(15 nm)/NPB:C545T(x%, 20 nm)/Alq3:C545T(4%, 20 nm)/Bphen(35 nm)/LiF(1 nm)/Al (200 nm), where x is the doping concentration. When the doping concentration is 3%, the device has the best photoelectric properties, which is named as device B1.The reference device B2 is prepared based on ITO, for the analysis of microcavity effect. B1 and B2 CIE are (0.2889, 0.620) and (0.3168, 0.5571), so the micro-cavity device could emit more green light. At 100 mA/cm2, the brightness of devices B1 and B2 is 5076 cd/m2 and 4818 cd/m2, and the maximum brightness of the both devices are 9277.7 cd/m2 and 10440 cd/m2. At 100 mA/cm2, luminance efficiency of devices B1 and B2 are 6.0 cd/A and 5.61 cd/A, and the luminance efficiency of the both devices are 8.6 cd/A and 7.97 cd/A. Compared with the reference devices, green microcavity device has a higher current efficiency and better color purity, which attributes to the microcavity effect.