Abstract: Global Navigation Satellite System (GNSS) has been developed for more than half a century, and it can not only provide users with navigation, positioning and timing services, but also be used for remote sensing of the Earth, and its applications are beyond imagination. Based on the application of GNSS-R, this paper systematically introduces the basic concepts and signal characteristics of GNSS-R, focuses on the land surface remote sensing applications, and analyzes the possible future development directions, which can provide an important reference for the application of GNSS-R.