Abstract: The hazardous exhaust gases, such as chlorine and iodine which are emitted from chemical oxygen-iodine laser (COIL), are harmful to air quality and personnel health in workplace. In this paper, based on the Gauss point source diffusion mode, exhaust gas diffusion model of COIL is established in the light wind or windless conditions. During the 15 minutes operating period of COIL, chlorine and iodine are accumulated in the air. The spatial distribution of concentration at the height of 1.5 m is calculated at the distance of 500 m away from the laser. Five sampling points were selected according to the spatial distribution of the pollutants concentration. In the measurement, Chlorine and iodine were collected simultaneously by using sodium sulfite solution as absorber. The concentrations of Cl- and I- in the absorption solution were measured by ion chromatography. The results show that the maximum concentration of chlorine was 0.200 mg/m3 in situ and the iodine concentration was under the detection limit of 0.030 mg/m3. Both of them are much less than the allowed concentration limit of harmful materials (1 mg/m3) specified in national occupational health standard.