It is considered that the efficiency of fluorescent material based organic light emitting diodes can be enhanced by introducing a phosphorescent sensitizer. In the present work, devices with emission layers (EML) of fac-tris(2-phenylpyridinato-N,C^2′) iridium (Ⅲ) (Ir(ppy)3)-sensitized-fluorescent materials were fabricated. Ir(ppy)3 was co-doped with DCJTB and rubrene in PVK matrix, respectively. When the doping ratio was proper, pure emission from fluorescent material can be achieved. Furthermore, the sensitizing mechanism and effect were analyzed. A weak effect between Ir(ppy)3 and DCJTB was found. It was deduced that the weaker sensitizing effect is related to the poor film appearance.