Molybdenum disulfide (MoS2) has good thermal and chemical stability and relatively high mobility in the environment. It has been used in the applications of gas sensors, photodetectors and field effect transistors. Oxygen-doped molybdenum disulfide (MoS2-xOx) generated by oxygen-assisted technology can not only regulate the size of MoS2 single crystal, but also improve the photoluminescence intensity of MoS2 single crystal. MoS2-xOx films were prepared and their optical properties were investigated in this paper. First, radio frequency reactive magnetron sputtering technology was used to prepare the precursors of MoS2-xOx films; next, the precursors in natural environment for 60 d were oxidized; finally, the MoS2-xOx films after a thermal annealing process were obtained. Herein, the angle between the sputtering plume and the glass substrate was specifically varied. The optical properties of MoS2-xOx films were investigated. X-ray photoelectron spectroscopy was used to analyze the elements and valence states of the samples. Scanning electron microscopy results show that the surface morphology is optimal at an angle of 45° (θ=45°) between the sputtering plume and the substrate. UV-Vis spectrophotometry results show that the optical band gap of the MoS2-xOx films decreasing as the thickness and oxygen content increasing. COMSOL Multiphysics software was utilized to simulate the transmittance of MoS2-xOx films, and the theoretical and experimental results agree well. The results of this paper will provide experimental data reference for the application of MoS2-xOx in the field of optical devices.