Abstract: 【Objective】 This study aimed to investigate the effective components with antimicrobial activity in extracts of Morinda citrifolia fruits against the coffee anthracnose and analyze， thereby providing a theoretical basis for the control of coffee anthracnose and the development and utilization of green pesticides.【Method】 Morinda citrifolia fruits were extracted with 90% ethanol to obtain crude ethanol extracts， which were subsequently fractionated using solvents of diffe-rent polarities （petroleum ether， ethyl acetate， and n-butanol）. The n-butanol extract was further separated and purified through silica gel column chromatography， thin-layer chromatography， and semi-preparative high-performance liquid chromatography. Components exhibiting antimicrobial activity against the coffee anthracnose pathogen were tracked， and the structures of isolated and purified compounds were identified using nuclear magnetic resonance （NMR） spectroscopy and mass spectrometry （MS）. Antimicrobial activity of the compounds was evaluated， and their effects on mycelial morphology of the coffee anthracnose pathogen were examined.【Result】 The n-butanol extract showed the strongest anti-microbial activity. Eleven fractions （Fr.1-Fr.11） were obtained， among which Fr.5， Fr.7， Fr.8， and Fr.9 exhibited inhibitory rates of 48.26%， 51.25%， 50.50%， and 55.71%， respectively. Further isolation and purification yielded four compounds from the four fractions， identified as quercetin， scopoletin， 7-hydroxycoumarin， and trans-4-hydroxycinnamic acid， all of which were phenolic compounds. Validation of antimicrobial activity of the four compounds demonstrated that trans-4-hydroxycinnamic acid had the strongest inhibitory effect， with an inhibition zone diameter of 1.92 cm. Scanning electron microscopy revealed that untreated mycelia of the coffee anthracnose pathogen were smooth and regular， whereas quercetin caused slight shrinkage； scopoletin and 7-hydroxycoumarin caused severe shrinkage and flattening； trans-4-hydroxycinnamic acid resulted in pronounced shrinkage， collapse， and breakage of the mycelia， suggesting that these compounds could exert antimicrobial activity by disrupting mycelial structure.【Conclusion】 Extracts of Morinda citrifolia fruits contain components with antimicrobial activity against the coffee anthracnose pathogen. Among the four isolated and purified active compounds， trans-4-hydroxycinnamic acid exhibits the strongest antimicrobial effects， indicating prospects of its application in ecofriendly control of coffee anthracnose.