Most of functional magnetic resonance imaging(fMRI)studies have employed task-related paradigm to explore brain response to an external stimulus.However,the brain is very active in the absence of any specific experimental tasks and the spontaneous activity exhibits coherent low-frequency synchrony.Studies on resting-state brain activity have provided insight into the intrinsic activity mechanism of the brain.In this study we review recent popular methods on resting-state functional connectivity and their preliminary applications to clinical diseases.