Indium tin oxide (ITO) films were deposited on acrylics by low temperature reactive magnetron sputtering. The effects of oxygen flow and bias voltage on the microstructure, surface morphology and bonding state of films were evaluated. In this investigation, X-ray photoelectron spectroscopy, X-ray diffraction, Atomic force microscope were used. It was found that the grain size of ITO films increased and surface roughness decreased with the increase of oxygen flow rate. The XPS spectra of In 3d and Sn 3d indicated that the oxygen flow had little effect on the binding energy of ITO films. The relative strength of O-II(2-) increased, while that of O-1(2-) decreased with increasing oxygen flow rate. The grain size increased with the bias voltage. However, at a maximum voltage of -90 V fine grains were detected due to the formation of numerous nuclei resulting from bombardment of high energy particles. The bias voltage had little effect on the bonding state of In, Sn and O ions.