In order to study characteristics of CO2 laser spectrum in 9R band and satisfy the need of laser interaction with matter, technology of coating for selecting wavelength was used firstly to make laser in 9R band output lonely from TEA CO2 laser. Then through single pulse discharge experiment, wavelength of CO2 laser and quantity of laser spectrum was analyzed by CO2 laser spectrum analyzer. Energy meter was used to measure the proportion of each laser spectrum in the single pulse energy. The changes about wavelength, quantity and energy proportion of CO2 laser spectrum in 9R band were studied by changing transmittance of output mirror, curvature radius of total reflector and proportion of working gases. Experiment results show that several adjacent CO2 laser spectrums in 9R band have been output meanwhile, and these spectrums can be changed with the change of transmittance of output mirror, curvature radius of total reflector and proportion of working gases.