Eucommia ulmoides oliv. leaf extract capable of protecting health of kidney function, and preparation and detection methods thereof

A preparation method for a Eucommia ulmoides Oliv. leaf extract, specifically comprising the following steps:

• 1) soaking the coarse powder of Eucommia ulmoides Oliv. leaves or mixed coarse powder of Eucommia ulmoides Oliv. leaves and male flower in water, and then adding a complex enzyme for enzymolysis and filtration to obtain drug residues and extracting solution I;
• 2) adding ethanol to the drug residues prepared in step 1) for extracting for 1-2 times;
• and after screening and filtering, obtaining drug residues and extracting solution II;
• 3) adding water to the drug residues prepared in step 2), and after extracting for 1-2 times, filtering to obtain extracting solution III;
• 4) concentrating the extracting solution I, the extracting solution II and the extracting solution III respectively;
• cooling the concentrates to room temperature and then mixing the concentrates;
• standing and then filtering;
• and spray-drying the filtrate to obtain the Eucommia ulmoides Oliv. leaf extract.