In order to understand the development process and the construction level of the infrared early warning satellites (IEWS), the system of US infrared early warning satellite is researched. The system of IEWS is one part of US anti-missile warning system, and the warning ability directly influences the efficiency of US anti-missile system. The development history of the systems of US IEWS is summarized. The research situation, working feature and ability of object detection of defense support program (DSP), space-based infrared system (SBIRS) and space tracking and surveillance system (STSS) are mainly introduced. Furthermore, the deployment situation of the satellites is analyzed based on satellite tool kit (STK). Based on that, the development enlightenment of US IEW