Abstract: The metallic supersonic nozzle of chemical oxygen-iodine laser(COIL) needs heating to keep warm in use, which makes its structure complicated and the failure rate is high. Several materials are considered to be suitable for fabricating non-heating supersonic nozzles. As an example, the temperature field of the nozzle made of polyimide is simulated numerically to verify the feasibility of the non-metallic non-heating nozzle. The results indicate that the nozzle made of polyimide can prevent heat transmitting and iodine vapor cooling effectively and meet the requirements of laser nozzles.