The photoluminescent and electroluminescent characteristics of a blend polymer system consisting of a novel fluorene-carbazole copolymer (PFC) and poly(vinylcarbazole) (PVK) were investigated. Three OLED devices with the structures of indium-tin-oxide (ITO)/PVK:PFC/bathocuproine(BCP)/tris-(8-hydroxylquinoline)-aluminum (Alq3)/Mg∶Ag, indium-tin-oxide(ITO)/PFC/bathocuproine(BCP)/Alq3/Mg∶Ag and indium-tin-oxide(ITO)/PVK/ bathocuproine(BCP)/Alq3/Mg∶Ag respectively, were fabricated. The optoelectronic properties of the devices were measured. The results demonstrated that PVK in the blend system effectively restrained the formation of PFC excimers in solid films. Light emission of the device with blend system shifted with the variation of applied electric field, and variable color ranging from green to blue could be obtained. The luminance of blue light reached 1650cd/m2 when the drive voltage was higher than 7V. It was inferred that an energy transfer process from PVK to PFC might have occurred in this blend system.