Compact Dewar is not only one of the development directions of cooled infrared detector assembly but also the need for miniaturization and integration of future infrared imaging system. Dewar provides optical, mechanical and electrical interfaces for the detector assembly, so its compact design requires comprehensive consideration of refrigeration capacity, detection performance, vacuum performance and system application. Combined with the structure composition and working principle of Dewar, the method and influence of compact design are analyzed.The research has a better inspiration and guidance for the design of the Dewar.