Endophytic fungi of Poly gala sibirica collected from Shuangjiang County of Yunnan Province were isolated and purified with traditional culture method,then these fungi were identified based on ITS se-quences.The fermentation extracts of the fungi were screened for acetylcholinesterase inhibitory activity to ex-plore the diversity of endophytic fungi in P.sibirica and their potential for treating Alzheimer's disease.The find-ings revealed that a total of 23 strains of endophytic fungi,including 18 from aerial tissues and 5 from the root of P.sibirica,were isolated.These fungi belonged to 13 genera,11 families,8 orders,4 classes and 1 phylum of Ascomycota.The dominant genera were Colletotrichum,Epicoccum and Fusarium.The inhibitory activities of methanol extracts of the 23 strains against acetylcholinesterase(AChE)were determined by modified Ellman's method.At a concentration of 0.5 mg/mL,12 of the strains showed moderate or high inhibitory effect against AChE(inhibition rate>30%).The strain Fusarium oxysporum PSA008 exhibited the most potent inhibitory effect on AChE with inhibition rate of 75.35%,and other 2 strains(Boeremia exigua PSA002 and Penicillium brefeldian-um PSB007)also showed high AChE inhibitory activity(inhibition rate>50%).UPLC-Q-TOF/MS was used to analyze the methanol extracts from rice culture of 3 strains of fungi,including PSA002,PSA008 and PSB007.The results showed that the response intensity and quantity of mass spectrum data points of the 3 samples were appar-ent and different,and compared with rice medium,there were also differences.The results indicated that the meta-bolic transformation of these fungi formed certain chemical diversity components.This study can provide basic research materials and a theoretical basis for further exploration of related compounds with AChE inhibitory activ-ity.