Polymer light emitting diodes (PLEDs) with ITO/PEDOT:PSS/MEH-PPV/LiF/Al structures were prepared by spin coating method on the patterned ITO(indium tin oxide)/glass substrates. MEH-PPV [Poly(2-methoxy-5(2-ethylhexoxy)-1,4-phenylenevinyle)] and PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)] polymers were used as the light emitting and hole transport materials. The dependence of the plasma treatment of ITO anode films on the optical and electrical properties of the PLEDs was investigated. The sheet resistances increased with increasing the plasma intensities from 40W to 300W in RF power. In contrast, the surface roughness was improved as the plasma intensity increased. The maximum current density and luminance were found to be about 97.5 mA/ and 55 cd/m2 at 8 V for the PLED sample coated on ITO/glass substrate with plasma treatment of 100W for 30s under 40 mtorr O2 pressure.