Using direct-current reactive magnetron sputtering technique, a series of silver oxide (AgxO) films were deposited at a substrate temperature of 250 ℃ by modifying the reactive pressure (RP). Effect of the RP on the film structure and optical properties was investigated by X-ray diffractometry, energy dispersive spectroscopy and spectrophotometry. An evolution of the phase structure from biphased (AgO+Ag2O) to single-phased (Ag2O), and then to biphased (Ag2O+AgO) occurred with the RP increasing from 0.5 to 3.5 Pa for the AgxO films. Single-phase Ag2O film, specially, was deposited at RP=2.5 Pa, which was capable of lowering the threshold of thermal decomposition temperature of the AgxO film. The film transmissivity in transparent region increased with the RP increasing, while the film reflectivity and absorptivity decreased with the RP increasing. This result is attributed to the evolution of the phase structure and the decrease of the film thickness. The absorption edge of the biphased (AgO+Ag2O) AgxO film was located near 2.75 eV, whereas the absorption edge of the single-phase (Ag2O) and Ag2O-dominated biphased (Ag2O+AgO) AgxO film was located near 2.5 eV.