Abstract: The law of infrared spectral and bands radiation characteristics of water sprays in the atmospheric windows, 3-5 m and 8-14 m, was researched. Through the research on spectral radiation characteristics of water sprays, a kind of approximate symmetry relationship between spectral scattering coefficients and spectral absorption coefficients was discovered. The axis of symmetry is just the 1/2 of the spectral extinction coefficients. The symmetry relationship was found to be more obvious along with the increase of the average droplets radiuses. Though the research on the bands radiation characteristics in 3-5 m and 8-14 m of water sprays, a group of approximate formulas for calculating the bands attenuation coefficients including extinction, scattering and absorption were founded. It's proved by error analyzing that the method mentioned above can ensure the relative errors of the three bands attenuation coefficients be less than 5%.