In this work, firstly; CO2 laser which is a very important among the molecular lasers, had been set up. Then; with CO2 laser which can produce relatively more powerful laser than the other laser types do , the dependence of output power of laser on temperature, pressure of gas mixture, input power, brewster angle has been investigated. Besides, by means of the observation of the output power as a function of input power, the efficiency of the system has been discussed. In addition to that some molecular properties of CO2 molecule related to that topic have been calculated by CNDO and MOPAC.