The purpose of this study was to explore the in vitro α-glucosidase inhibitory activity of Rhodiola crenulata extract and the main active substances with inhibitory effect.An in vitro α-glucosidase inhibitory system was constructed,its inhibitory activity was measured,and the type of inhibition was determined by enzyme inhibition kinetics.Then,ultra-high performance liquid chromatography-mass spectrometry (UHPLC-QE-MS) and molecular docking were used to further explore the main compounds in the extract that inhibit the activity of α-glucosidase.The results showed that the extract of R. crenulata had a good inhibitory effect on α-glucosidase,with IC₅₀ of 1.538 mg/mL,which was a mixed reversible inhibition type of competitive and non-competitive.A total of 1 245 compounds were detected by UHPLC-QE-MS,among which fatty acids,terpenes and their derivatives,flavonoids were the three most common compounds,with 107,85 and 66 compounds,respectively.Secondly,a variety of substances such as phenols,amino acids,and sugars were identified.Molecular docking showed that 11 of the 20 compounds with relatively high content had binding to α-glucosidase.The (+)-epicatechin binding energy (-17.08 kJ/mol) was the lowest and binding activity was the best.Caffeic acid forms up to 5 hydrogen bonds,which are connected to His-515,Arg-437,Glu-432,and His-348 residues respectively.Caffeic acid,L-malic acid,quercetin and tyrosol have the same binding site Arg-437.This study provided basic research for the development of natural α-glucosidase inhibitors and the utilization of R. crenulata resources.