NOVELTY - A polyphenol is extracted in Geranium wilfordii by uniform paste crushing enzymolysis, constant temperature enzymolysis, and negative pressure cavitation auxiliary extraction. The step (A) includes preparing 5-100 U/mL enzyme solution using water, mixing enzyme solution and dried G. wilfordii at 20-30 mL/g volume ratio of solution and material, and making paste uniform for 1-2 minutes by uniform paste machine. The step (C) includes transferring enzymolysis solution to negative pressure cavitation extractor, and extracting for 1-3 times and 10-30 minutes each time.    USE - Method is used for extracting polyphenol in G. wilfordii (claimed).    ADVANTAGE - The content of total polyphenol in extract can reach 156.14 mg GAE/g. The content of polyphenol active ingredients of gallic acid, corilagin and G. wilfordii can reach 9.58 mg/g, 6.87 mg/g and 19.82 mg/g. The method is improved by 30-67% in comparison with traditional hot reflux method. The method has high extraction rate, safe operation without high-temperature heating and organic solvent, and is green and environment-friendly; and is suitable for industrial production.    DETAILED DESCRIPTION - Polyphenol is extracted in geranium wilfordii by uniform paste crushing enzymolysis, constant temperature enzymolysis, and negative pressure cavitation auxiliary extraction. The step (A) includes preparing 5-100 U/mL enzyme solution using water as solvent, mixing enzyme solution and dried G. wilfordii at 20-30 mL/g volume ratio of solution and material, and making paste uniform for 1-2 minutes by uniform paste machine. The step (B) includes transferring uniform paste liquid to constant temperature table, and enzymolyzing for 3-6 hours at 30-50 degrees C, where rotating speed is 100-120 rpm. The step (C) includes transferring enzymolysis solution to negative pressure cavitation extractor, extracting for 1-3 times and 10-30 minutes each time, concentrating extraction liquid and drying after filtering at reduced pressure, and obtaining G. wilfordii extract containing polyphenol.