The conductivity of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) film is improved by simply mixing PEDOT:PSS solution with ethanol for the film deposition, and the performance of quantum-dot light-emitting diodes (QD-LEDs) is significantly enhanced with ethanol treated (ET- treated) PEDOT:PSS as the hole injection layer (HIL). Comparing with the pristine PEDOT:PSS based device, the current density of device with ET-treated PEDOT:PSS as the HIL is increased by 18%, from 50 to 59mA/cm2, at operating voltage of 5V, and the maximum current efficiency is enhanced by 12.5%, from 10.4 to 11.7cd/A, which is due to the improved conductivity of ET-treated PEDOT:PSS film. With atomic force microscopy (AFM) measurements, we demonstrate that the improvement of the conductivity of PEDOT:PSS film is due to the decreased PSSH amount after solvent treatment, reducing the thickness of PSSH insulating shell, leading to an efficient charge transport across the PEDOT chains.