Abstract: Low temperature extended area blackbody,as a standard radiation source of infrared spectrum,is generally used in the calibration of IR sensors and thermal imagers.With the development of infrared technology,its application has been more and more popular and extended to low temperature area.Temperature uniformity is an important parameter of the extended area blackbody.A kind of uniform temperature structure which can improve the temperature uniformity is introduced.The experimental results show that the structure can make the extended area blackbody temperature uniformity better than 0.2K.