The electrical and optical properties of ZnO ultrafine particle (UFP) films prepared by a new de gas discharge activated reactive deposition technique were investigated. IR spectra and work function were used to study the samples. The results show that In a vs 1000/T accords with the Arrhenius equation at 227-300 degrees C, the absorption edge is near 480 nm, IR eigen absorption peaks of ZnO (UFP) films shift to high energy (short wavelength) with decreasing particle size. The work function changes with gas pressure was discussed.