Background Near infrared spectroscopy (NIRS) is a new method for monitoring regional cerebral oxygen supply and demand balance with sensitive, fast, and real-time, continuous and noninvasive features. Some detail information on the regional cerebral cortex blood perfusion and oxygen supply and demand balance can be obtained by NIRS percutaneous detecting regional cerebral oxygen saturation (rSO2). Objective The aim of this review is to outline the near infrared spectroscopy for monitoring regional cerebral oxygen saturation and provide practical reference data for clinical work. Content This review includes three aspects: the principle of NIRS monitoring rSO2, its clinical application and affected factors. Trend NIRS monitoring rSO2 is mainly applied to monitor oxygen supply and demand balance and the changes of cerebral perfusion to prevent cerebral ischemia and hyperperfusion, and which has vast applied foreground on noninvasive monitoring intracranial pressure and evaluating the clinical treatment of cerebrovasospasm so on.