Abstract: The aim is to establish a non-invasive method on quantification measurement of cerebral blood flow. Dynamic radionuclide angiography was performed in 20 normal youth subjects after bolus injection of 99mTc-ECD into the right cubital vein of the right arm. ROIs were hand-drawn over the aortic arch and bilateral brain hemispheres to produce time-activity curves respectively which were corrected by dead-time. The unidirectional influx rate (ku), brain perfusion index (BPI) were obtained by graphical picture analysis. And then BPI was converted to CBF. The mean of the CBF the two groups are 54.5±5.1 ml/100g/min（5～16 years）and 49.4±3.2ml/100g/min（22～32 years）respectively. There is significant deviation between the two groups. This method is non-invasive, operable and in favor of clinical application.