High-sensitivity trace oxygen sensing based on far-ultraviolet absorption spectroscopy was realized. The far-ultraviolet absorption spectrum of oxygen in the wavelength range of 170-200 nm at normal pressure was measured, and the maximum oscillation absorption peak occurred close to 180.18 nm. Through error analysis, the optimal wavelength range for accurate and sensitive oxygen measurements by ultraviolet absorption spectroscopy was identified as 180-189 nm. A total column (CL) calibration curve for oxygen was established, and the maximum optical path length (L1) of the system was determined to be 0.75(3) m by comparing the oxygen absorption with and without the sample cell. The oxygen detection sensitivity was 232 m-1, and the lowest detection limit was 12 ppm at the L1 optical path length. The highly sensitive trace oxygen sensing based on far-ultraviolet absorption spectroscopy exhibited significant potential for application with regard to nitrogen protection.