The invention discloses a quantitative laser blood flow detection method and provides a quantitative laser blood flow detection method by adopting laser illumination based on characteristic differences of dynamic laser speckle time domain and space domain statistics. The quantitative laser blood flow detection method is a non-intrusive method having high temporal-spatial resolution and eliminating static element interference in fixed exposure time. Compared with other existing laser blood flow detection technologies, the quantitative laser blood flow detection method has the advantages that no additional device for exposure time change is needed, and the static element interference can be eliminated and quantitative blood flow measurement is completed only in the fixed exposure time. The quantitative laser blood flow detection method is applicable to study on cerebral function imaging, nerve physiology, brain disease pathology and efficacy evaluation and clinical medical diagnosis and treatment.