Abstract: With the construction and development of terrestrial mobile communication systems and the explosive growth of mobile Internet services, diversified mobile communication needs and application scenarios continue to emerge. The Internet of Things (IoT) technology has developed rapidly in recent years, and has been widely constructed and applied. Satellites are more suitable for large-area data collection and IoT services because of their wide-area coverage and invulnerability. In recent years, with the improvement of satellite communication technology capabilities and the optimization of the industrial chain, commercial aerospace has flourished, and the integration of space and terrestrial networks has become a trend. In recent years, dozens of space-based IoT systems have emerged in the world, some of which have been put into engineering construction and application, and progress has been made in the system architecture and system design of the space-based IoT. This paper conducts research on the development and construction application of satellite Internet of Things technology. The construction planning, capability positioning, system architecture, constellation strategy, communication technology, frequency resources, market application of Orbcomm, Kepler, SpaceMobile, ELO and other low-orbit constellation IoT systems were comprehensively analyzed, and the development trend and important issues of the space-based IoT constellation system were summarized.