Raman-differential absorption method was introduced for monitoring ozone concentration in the bottom of troposphere. The intensity of the Raman spectra of N2 and O2 was analyzed and calculated. The retrieving equation of ozone’s concentration was presented based on the different absorption of ozone to the Raman spectra of N2 and O2 in ultraviolet (UV). A Raman-differential absorption lidar system was designed. The system collected Raman scattering signals of N2 and O2 by two channels, and concentration of ozone can be retrieved by these pairs of signals. The specifications of interference filters in two channels were presented by analyzing the sources of noises. The influences and relative errors of monitoring ozone in this method were analyzed, because SO2 and NO2 also absorb Raman scattering signals of N2, O2 in UV. Finally, vibrational Raman signals of N2 and O2 were simulated by the ozone data which monitored by AML-2 differential absorption lidar (made in Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences). The simulation results indicate that Raman-differential absorption method is feasible for monitoring ozone concentration in low atmosphere.