On the basis of measured expression from the rate equation, the stimulated-emission cross sections of seven lines of CO2 laser from 00?-10? transition at different conditions were measured by means of a pulse-amplification-gain technique, and 83 values of were obtained. Theoretical values of were calculated according to an analytical expression from the definition of The measured values of were compared with theoretical ones, and they are in satisfactory agreement.Finally,an analysis was made of the dependence of on the rotational quantum number J,its temperature and the pressure of active gas mixture.