The invention provides a method for extracting and separating Vicenin-2 from desmodium styracifolium. The method includes the following steps that reflux extraction is performed on the desmodium styracifolium through ethanol, and desmodium styracifolium extracts are obtained; multistage chromatographic separation is performed on the extracts through alcohol systems, wherein first chromatographic separation is performed on the extracts through the first alcohol system so that first separated parts can be obtained, second chromatographic separation is performed on the first separated parts through the second alcohol system so that second separated parts can be obtained, and third chromatographic separation is performed on the second separated parts through the third alcohol system so that the Vicenin-2 can be obtained. The invention further provides a system implementing the method. When the Vicenin-2 is separated and extracted from the desmodium styracifolium by means of the method and/or the system, the operation of the technology is simple, production time is short, the product yield is high, the purity is high, and the Vicenin-2 with the purity larger than 98% can be obtained.