in vitro evaluation of the antioxidant activity of plant compounds or plant extracts is an important aspect of functional factor research. The DPPH(1-diphenyl-2-picrylhydrazyl) radical scavenging assay is widely used for antioxidant activity evaluation of plant compounds and extracts. However, this method lacks a standardized program so that results from different experiments may be difficult to compare with each other. The present review presents a comprehensive overview of the principle, measurement procedure and wavelength, initial DPPH free radical concentration, reaction time, calculation of the scavenging rate, expression of results and evaluation indices. Several external factors influencing the DPPH assay are also discussed.