The invention provides a technology for extracting high-purity oxyresveratrol from morus alba L.. The technology is implemented as follows: dried and smashed morus alba L. is repeatedly extracted for 2-3 times with an ethanol solvent, filtrate is mixed and concentrated until the solid content is 10%-15%, ethyl acetate is added to be extracted for 2-3 times, and ethyl acetate solutions are mixed; the ethyl acetate solutions are concentrated to paste, ethanol is added to sufficiently dissolve the paste substance, a decolorizing agent whose mass is 20-30 times that of the paste substance is added, ethanol is added again, the mixture is sufficiently stirred and filtered, the filtrate is obtained and concentrated to the alcohol-free state, the mixture is left to stand for 20-30 hours in the low-temperature environment and filtered, and filter residues are obtained; petroleum ether is added, the mixture is sufficiently stirred and left to stand for 20-30 hours at the low temperature, the mixture is filtered, filter residues are obtained, and an oxyresveratrol extract is obtained. The purity of oxyresveratrol after separation and purification is up to 90% or higher, the recovery rate is up to 85% or higher, and the technology is simple, easy and simple to operate, low in cost and capable of realizing large-scale production.