The pathophysiological mechanism of depressive disorder is still unclear.Functional nearinfrared spectroscopy （fNIRS） is a useful neuroimaging technique based on hemodynamic principles for the non-invasive investigation of brain in motion. It is widely used in psychiatry and considered to be a potential auxiliary diagnostic method based on the current evidence. In addition， fNIRS can be combined with other neuromodulation therapies to detect changes in hemodynamics and oxygenation status of the cerebral cortex， providing valuable advices for setting related technical parameters and prognosis.