Aiming at the small consumer UAV with low-altitude,infrared radiation model of the target and radiation parameter model of the background were established by theoretical modeling and experimental measurement of flight temperature parameters,then the infrared detection range was obtained,and it is consistent with the measured results.For the target with weak infrared radiation,the more accurate infrared operating range can be gotten only carefully estimating the sunlight reflection and background noise.Through the analysis of the results,some advice is given for the design of future UAV infrared detection system.