NOVELTY - Preparation of active compounds from waste walnut shell comprises cleaning, drying and crushing walnut shell, adding aqueous acetone solution, heating and extracting at normal temperature or performing Soxhlet extraction or supercritical fluid extracting or microwave or ultrasonic-assisted extracting, filtering, concentrating, multiple extracting using, e.g. n-hexane and ethyl acetate and multiple dissolving using silica gel column chromatography and Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain active compounds (I)-(V).    USE - The active compounds (I)-(V) are used for preparing tyrosinase inhibitor (claimed) of mushroom tyrosine enzyme.    ADVANTAGE - The method is simple, economical, environment-friendly and has short production time. The product has high purity.    DETAILED DESCRIPTION - Preparation of active ingredients from waste walnut shell comprises: (A) cleaning walnut shell, drying in shade, crushing to granularity of 20-100 meshes, adding 5-99 vol.% aqueous acetone solution at mass ratio of 1:1-1:10, heating and extracting at normal temperature or performing Soxhlet extraction or supercritical fluid extracting or microwave or ultrasonic-assisted extracting 1-6 times where each is for 10 minutes-72 hours, filtering, concentrating filtrate at reduced pressure to 1-10% the original volume to obtain walnut shell concentrated extract; (B) adding 1-8 times water based on mass of concentrated extract, stirring, adding 1-8 times n-hexane and extracting 1-8 times, centrifuging to separate n-hexane, adding 1-8 times dichloromethane and extracting 1-8 times, centrifuging to separate dichloromethane, adding 1-8 times ethyl acetate and extracting 1-8 times, centrifuging to separate ethyl acetate, adding 1-8 times n-butanol and extracting 1-8 times, centrifuging to separate n-butanol, concentrating at reduced pressure and freeze-drying to obtain walnut shell n-butanol extracting phase powder; (C) dissolving walnut shell n-butanol extracting phase powder into methanol-water solution at normal pressure using Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain five streams comprising B1-B5, where methanol-water solution is the mobile phase and has volume ratio of 4:1-2:1; (D) dissolving sample in B2 stream into dichloromethane-acetone solution at sample to solution volume ratio of 6:1-3:1 at normal pressure using silica gel column chromatography to obtain B21 to B23 streams, where initial concentration ratio is 8:6-6:1 and dichloromethane-acetone solution volume ratio is 4:1-2:1; (E) dissolving sample in B22 stream into aqueous methanol solution at sample to solution volume ratio of 2:1-1:6 at normal pressure using Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain compound (I); (F) dissolving sample in B3 stream into aqueous methanol solution at sample to solution volume ratio of 1:1-1:3 at normal pressure using Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain B31-B34 streams; (G) dissolving sample in B33 stream into aqueous methanol solution at sample to solution volume ratio of 1:3-1:5 at normal pressure using Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain B331 and B333 streams and compound (IV); (H) dissolving sample in B333 stream into ethanol-n-hexane solution at sample to solution volume ratio of 2:1-1:4 at normal pressure using Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain compound (III); (I) dissolving sample in B4 stream into dichloromethane-methanol-water solution at volume ratio of 7:2:1 at normal pressure using silica gel column chromatography to obtain B42 and B43 streams and compound (V); (J) dissolving sample in B42 stream into aqueous methanol solution at sample to solution volume ratio of 2:1-1:2 at normal pressure using Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain B421-B423 streams; and (K) dissolving sample in B422 stream into ethanol-n-hexane solution at sample to solution volume ratio of 1:3-3:1 at normal pressure using Sephadex LH-20 gel (RTM: dextran gel) column chromatography to obtain compound (II).