The theories of rate equation and six-temperature model for CO2 lasers are used to describe the process of the dynamic emission in the electrooptically Q switched CO2 laser. The peak power and delay time of Q switched laser calculated by the two theories are well consistent with the experiments. The calculated pulse width of Q switched laser using the theory of rate equation is narrow and the tailing is too short. However, a theoretical analysis by using the six-temperature model is consistent with the measured waveform and the tailing is obvious. In addition, the processes of energy-transfer of all kinds of molecular levels are considered in the six-temperature model. So compared to the rate equation, the six-temperature model makes a better analysis.