The infrared radiation characteristics of axisymmetric and 2-D nozzles with aspect ratios of 1,4,8,12 and 16,have been experimentally studied.The nozzle flow is composed of the main gas stream and the secondary air stream in order to simulate the nozzle of turbofan engine.The spatial distributions of the infrared radiation intensity of 2-D nozzles have been obtained,and compared with that of the axially symmetric nozzles.