Diffusion　correlation　spectroscopy　(DCS)　is　a　relatively　new　methodology　that　has　been　extensively　used　for　the　noninvasive　monitoring　of　tissue　blood　flow.　This　technology　irradiates　the　tissue　surface　with　near-infrared　light,　calculates　the　light　intensity　autocorrelation　function　of　the　scattered　spot　on　the　tissue　surface,　and　computes　the　movement　of　red　blood　cells　to　realize　the　quantitative　detection　of　blood　flow　changes　in　tissues.　DCS　measurements　show　more　promise　for　the　noninvasive,　radiation-free,　continuous　and　real-time　monitoring,　wide　application　range,　and　low　detection　requirements　of　tissue　blood　flow　than　the　other　blood　flow　monitoring　methods　such　as　laser　Doppler　flowmetry　(LDF),　magnetic　resonance　imaging　(MRI),　and　positron　emission　tomography　(PET).　Moreover,　DCS　technology　can　be　utilized　for　the　bedside　monitoring　of　tissue　blood　flow.　The　DCS　technique　is　mainly　introduced　in　which　its　theoretical　background,　instrumentation,　progress,　and　clinical　applications　are　included,　as　well　as　its　future　development　prospects　are　discussed.