Abstract: The in vitro susceptibility test was used to evaluate the activity of eugenol against Malassezia, and the interaction between eugenol and traditional antidandruff drugs was studied by the checkerboard microdilution method. The minimum inhibitory concentration (MIC) of eugenol was 312.50 μg/mL and the minimum fungicidal concentration was 625.00 μg/mL. Eugenol combined with ketoconazole showed a synergistic effect, and combined with zinc pyrithione (ZPT), climbazole, and piroctone olamine (OCT) respectively showed additive effects. Combined use can reduce the minimum effective concentration of each drug by 50%~75%. The toxicity of eugenol to keratinocytes was evaluated by MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromid) assay. The results showed that the IC₅₀ of eugenol was 320.93 mg/L, which is higher than that of traditional antidandruff agents. This indicated that eugenol has higher safety at the cellular level. The mechanism of eugenol against Malassezia was studied by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). It was found that eugenol achieves fungicidal ability by destroying cell wall and internal membrane structure of Malassezia. These results provided a theoretical basis for the application of eugenol in antidandruff products.