A ultraviolet high spectral lidar for Rayleigh temperature measurement is an effective tool for detecting the temperature profile. At present, the light with wavelength of 355 nm is used in the ultraviolet high spectral lidar for Rayleigh temperature measurement. However, the solar backgroun radiation has a great influence on the signal-noise ratio (SNR), and the distance and the accuracy of temperature measurement are restricted. To realize the full-time measurement for atmospheric temperature, a 266 nm ultraviolet high spectral lidar system for Rayleigh temperature measurement based on Fabry-Perot etalon is presented. Because there is no 266 nm light in the solar background radiation, the effect of ozone on the 266 nm light absorption is only needed to be considered, and then the full-time measurement for atmospheric temperature is realized. The spectral widths, transmission rates, SNR of echo signal and temperature errors of 266 nm and 355 nm ultraviolet high spectral lidar systems for Rayleigh temperature measurement are simulated and analyzed based on main parameters, such as pulse energy, diameter of telescope, receiving view field angle of telescope, concentration of ozone and solar background light intensity. Results show that the influence of atmospheric molecular and aerosol scattering on light at 266 nm is much larger than that of light at 355 nm. In the daytime, the effective measurement distance of 266 nm ultraviolet high spectral lidar system for Rayleigh temperature measurement is about 4 km, which is 2.9 km far than that of 355 nm ultraviolet high spectral lidar system for Rayleigh temperature measurement. The effective measurement distance of 266 nm ultraviolet high spectral lidar system for Rayleigh temperature measurement is about 6 km in the nighttime. When the measurement distance is smaller than 5 km, the temperature error of 266 nm ultraviolet high spectral lidar system for Rayleigh temperature measurement is 10 K less than that of 355 nm ultraviolet high spectral lidar system for Rayleigh temperature measurement in the daytime. The 266 nm ultraviolet high spectral lidar for Rayleigh temperature measurement can be used to measure atmospheric temperature in the daytime and in the nighttime.