The U.S. space-based early warning satellite system is an important part of the missile defense system， and the research on its development status and capabilities is of great significance. In order to support China’s fundamental research and engineering development on space-based optical early warning，the research progress and achievements of the US "next generation overhead persistent infrared" （OPIR） early warning satellite are reviewed based on the analysis of the development history， system composition and main issues of the two generations of space-based early warning satellites of the US defense support program （DSP） and space-based infrared system （SBIRS）. The research status of constellation planning， sensor payloads development， ground data processing system， OPIR data standardization is summarized in detail. It is suggested that the research should focus on building the target infrared image data set， developing wide-field of view （WFOV） data processing algorithms， developing search and tracking integrated large area array payload technology， strengthening satellite near-field perception and defense.