A flexible organic light-emitting diode (FOLED) was fabricated on an indium tin oxide (ITO) plastic substrate by inserting an UV-curable epoxy resin as a buffer layer between the plastic substrate and ITO film. The structure of the FOLED devices was ITO/NPB (50nm)/Alq(50nm)/Mg:Ag(100nm). The surface morphology of three kinds of substrates was characterized by atomic force microscopy. The results show that with a spin-coated buffer layer, the surface roughness of ITO films on PET substrate decreased from 1.08to0.34nm. With the assistance of UV-sensitive resin, the adhesive force between the plastic substrate and ITO anode was significantly increased. The maximum luminance of FOLEDs was enhanced from 2720to4860cd/m2 at 12V.