Oleuropein hydrolyzed products exhibit potent biological activities.To enhance oleuropein hydrolysis by cellulase,a natural deep eutectic solvent (NADES) was utilized to stabilize the cellulase enzyme.The DES-cellulase solvent system effectively promoted enzymatic hydrolysis of oleuropein.Factors such as temperature,pH,DES type and concentration were studied to determine their impact on the hydrolysis rate.Results showed that at 50 ℃ and pH=5,the hydrolysis rate of oleuropein was 1.7 times higher than that of buffer solution when using 10% (V/V) DES-5 (betaine:1,4-butanediol =1∶2,n/n) as solvent for 3 h.This study confirms that NADESs with choline chloride or betaine as hydrogen bond acceptor (HBA) and polyols as hydrogen bond donor (HBD) effectively enhance cellulase stability and promote oleuropein hydrolysis.These findings provide a scientific basis for the efficiently producing oleuropein enzyme hydrolyzed products.