Abstract: We developed a CW chemical oxygen iodine laser using extracavity power outputwhich has obtained small signal gain 1.6 × 10^-3cm^-1.Under the conditions that the Cl₂ flow rate is 30 mmol/s, the I₂ flow rate is 0.3 mmol/s and the cavity pressure is 200Pa,the power outputsof linear polarigation light were obtained from the experimental data:maximum values of poweroutput of 178W at the half extracavity,and 70.4W at the full extracavity, respectively.