Onchip refractive index sensing has broad application prospects in the fields of safety inspection, environmental monitoring, health diagnosis, food supervision, etc. Currently, the microring resonator refractive index sensor based on silicononinsulator platform has become a research hot spot due to its capacities on miniaturization and integration. In this paper, its principles are introduced firstly, and then, the latest research progresses in and abroad are sorted out according to the principles of detection, and also the advantages and disadvantages are analyzed and summarized simultaneously. Finally, the existing problems and future development trends of refractive index sensing based on silicononinsulator microring resonators are discussed.