Primary insomnia is a common sleep disorder， and its pathogenesis and changes in brain function remain unclear. With the development of functional magnetic resonance imaging（ fMRI）， more and more people use fMRI to study primary insomnia in order to elucidate its pathogenesis. fMRI can not only record the changes of brain microstructures， but also display the functional states of corresponding brain regions in the form of images， which makes it possible to study and clarify the relationship between brain microstructures and functions. This article reviews the research progress of resting-state fMRI in primary insomnia in order to provide reference for further study of primary insomnia.